Photoresist composition

ABSTRACT

A photoresist composition comprising an acid generator and a resin which comprises one or more structural units (a1) derived from a monomer (a1) having an acid-liable group, all of monomers (a1) showing a distance of Hansen solubility parameters between the monomer (a1) and butyl acetate in the range of 3 to 5, the distance being calculated from formula (1):
 
 R =(4×(δ d   m −15.8) 2 +(δ p   m −3.7) 2 +(δ h   m −6.3) 2 ) 1/2   (1)
 
in which δd m  represents a dispersion parameter of a monomer, δp m  represents a polarity parameter of a monomer, δh m  represents a hydrogen bonding parameter of a monomer, and R represents a distance of Hansen solubility parameters, and at least one of the monomers (a1) showing a difference of R between the monomer (a1) and a compound in which an acid is removed from the monomer (a1) in the range of not less than 5.

This application claims priority to Japanese Application No. 2016-097199filed on May 13, 2016. The entire disclosures of Japanese ApplicationNo. 2016-097199 is incorporated hereinto by reference.

FIELD OF THE INVENTION

The disclosure relates to a photoresist composition.

BACKGROUND ART

JP2014-115631A1 proposes a photoresist composition containing a resinwhich has not structural unit having an acid-labile group but astructural unit represented by formula (I) and a structural unitrepresented by formula (a4), a resin which has a structural unitrepresented by formula (II) and a structural unit having an acid-labilegroup, and an acid generator.

(In the formulae, R² represents a C3 to C18 alicyclic hydrocarbon group,R⁴ represents a C1 to C20 saturated hydrocarbon group having a fluorineatom, A²¹ represents a single bond or the like.)

SUMMARY OF THE DISCLOSURE

The disclosure provides following inventions.

[1] A photoresist composition comprising an acid generator and a resinwhich comprises one or more structural units (a1) derived from a monomer(a1) having an acid-liable group,

the monomer (a1) each showing a distance of Hansen solubility parametersbetween the monomer (a1) and butyl acetate in the range of 3 to 5, thedistance being calculated from formula (1):R=(4×(δd _(m)−15.8)²+(δp _(m)−3.7)²+(δh _(m)−6.3)²)^(1/2)  (1)in which δd_(m) represents a dispersion parameter of a monomer, δp_(m)represents a polarity parameter of a monomer, δh_(m) represents ahydrogen bonding parameter of a monomer, and R represents a distance ofHansen solubility parameters, and

at least one of monomers (a1) showing a difference of R between themonomer (a1) and a compound in which an acid is removed from the monomer(a1) in the range of not less than 5.

[2] The photoresist composition according to [1)]

wherein the resin further comprises a structural unit derived from amonomer (s) having no acid-liable group, and

R of the monomer (s) is not more than 6.7.

[3] The photoresist composition according to [2]

wherein the monomer (a1) each shows the difference in the range of notless than 2.8.

[4] The photoresist composition according to [1]

wherein the ratio of a structural unit derived from the monomer (a1)showing the difference in the range of not less than 4.5 is not lessthan 30% by mole with respect to all the structural units of the resin.

[5] The photoresist composition according to [1]

wherein the monomer (a1) is represented by formula (I):

in the formula, X^(a) and X^(b) represent an oxygen atom or a sulfuratom,

W² represents a C3 to C36 alicyclic hydrocarbon group which can have asubstituent and a methylene group of which can be replaced by an oxygenatom, a sulfur atom, a carboxy group or a sulfonyl group,

R¹ represents a C1 to C8 alkyl group in which a methylene group can bereplaced by an oxygen atom or a carboxy group,

R² represents a hydrogen atom or a methyl group,

A¹ represents a single bond or a C1 to C24 divalent saturatedhydrocarbon group where a methylene group can be replaced by an oxygenatom or a carbonyl group, and

X¹ represents a group represented by formulae (X¹-1) to (X¹-4):

where * and ** represent a binding position respectively, and **represents a binding position to A¹.

[6] The photoresist composition according to [1]

wherein the resin further comprises a structural unit having a lactonering and no acid-labile group.

[7] The photoresist composition according to [6]

wherein the structural unit having a lactone ring and no acid-labilegroup is a structural unit represented by formula (a3-4):

wherein R²⁴ represents a hydrogen atom, a halogen atom or a C1 to C6alkyl group which can have a halogen atom,

L^(a7) represents —O—, *—O-L^(a8)-O—, *—O-L^(a8)-CO—O—,*—O-L^(a8)-CO—O-L^(a9)-CO—O— or *—O-L^(a8)-O—CO-L^(a9)-O— where *represents a binding position to a carbonyl group, L^(a8) and L^(a9)independently represents a C1 to C6 alkanediyl group, and

R^(a25) in each occurrence represents a carboxy group, a cyano group ora C1 to C4 aliphatic hydrocarbon group, and

w1 represents an integer of 0 to 8.

[8] The photoresist composition according to [1]

wherein the resin further comprises a structural unit having a hydroxylgroup and no acid-labile group.

[9] The photoresist composition according to [1]

wherein the acid generator is represented by formula (B1):

wherein Q¹ and Q² each respectively represent a fluorine atom or a C1 toC6 perfluoroalkyl group,

L^(b1) represents a C1 to C24 divalent saturated hydrocarbon group wherea methylene group can be replaced by an oxygen atom or a carbonyl groupand a hydrogen atom can be replaced by a hydroxyl group or fluorineatom, and

Y represents an optionally substituted methyl group or an optionallysubstituted C3 to C18 alicyclic hydrocarbon group where a methylenegroup can be replaced by an oxygen atom, a carbonyl group or a sulfonylgroup, and Z⁺ represents an organic cation.

[10] The photoresist composition according to [1] further comprising aresin which comprises a structural unit having a fluorine atom and noacid-labile group.

[11] The photoresist composition according to [1] further comprising asalt which generates an acid having an acidity weaker than an acidgenerated from the acid generator.

[12] A method for producing a photoresist pattern comprising steps (1)to (5);

(1) applying the photoresist composition according to [1] onto asubstrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer; and

(5) developing the heated composition layer.

DETAILED DESCRIPTION OF DISCLOSURE

The indefinite articles “a” and “an” are taken as the same meaning as“one or more”.

In the specification, the term “solid components” means components otherthan solvents in a photoresist composition.

<Photoresist Composition>

The photoresist composition of the disclosure contains an acid generator(which is sometimes referred to as “acid generator (B)”) and a resinwhich comprises one or more structural units (a1) derived from a monomer(a1) having an acid-liable group. Such resin is sometimes referred to as“Resin (A)”.

The composition of the disclosure can contain another resin than Resin(A). The “another resin” is sometimes referred to as “Resin (X)”.

Further, the photoresist composition preferably contains a quencher(which is sometimes referred to as “quencher (C)”) and/or a solvent(which is sometimes referred to as “solvent (E)”) in addition to theResin (A) and the acid generator (B).

<Resin (A)>

Resin (A) has a structural unit having an acid-labile group (which issometimes referred to as “structural unit (a1)”). The resin ispreferably decomposed by an action of acid to decrease in solubility inbutyl acetate. Here the “acid-labile group” means a group having aleaving group capable of detaching by contacting with an acid to therebyform a hydrophilic group such as a hydroxy or carboxy group.

Resin (A) further has a structural unit having no acid-labile group(which is sometimes referred to as “structural unit (s)”).

The structural unit (a1) is derived from a monomer (a1) having anacid-labile group.

In the present disclosure, the monomer (a1) has specific Hansensolubility parameters as mentioned below.

Here, Hansen solubility parameter consists of three dimensions and isrepresented by the following coordinates. One of the coordinates is theparameter “δd”, determined from dispersibility of one substance, anotherone is the parameter “δp”, determined from dipole-dipole force of onesubstance, and the other is the parameter “δh”, determined from hydrogenbonding force of one substance. These parameters are related tosolubility of one substance.

The parameter “δd” is a coordinate which represents a level ofdispersibility, the parameter “δp” is a coordinate which represents alevel of dipole-dipole force, and the parameter “δh” is a coordinatewhich represents a level of hydrogen bonding force.

The definition and calculation as to Hansen solubility parameters aredescribed in “Hansen Solubility Parameters: A Users Handbook (CRC Press,2007)”, authored by Charles M. Hansen.

When Hansen solubility parameters, which coordinates are sometimesreferred to as “HSP coordinates”, of any compound have not beenconfirmed, the parameters can easily be calculated from their chemicalstructures by using a computer software “Hansen Solubility Parameters inPractice (HSPiP)” In the present application, as to butyl acetate andmonomers whose Hansen solubility parameters have been registered in adatabase, their registered data is used for calculating Hansensolubility parameters of monomers and a distance of the parameters. Asto monomers whose Hansen Solubility Parameters have not been registered,the parameters [δd, δp and δh] were calculated using HSPiP Version 4.1.

As to Resin (A), the monomer (a1) each shows a distance of Hansensolubility parameters between the monomer and butyl acetate in the rangeof 3 to 5, preferably 3.1 to 4.9, more preferably 3.2 to 4.9.

The distance is calculated from formula (1):R=(4×(δd _(m)−15.8)²+(δp _(m)−3.7)²+(δh _(m)−6.3)²)^(1/2)  (1)in which δd_(m) represents a dispersion parameter of a monomer, δp_(m)represents a polarity parameter of a monomer, δh_(m) represents ahydrogen bonding parameter of a monomer, and R represents the distance.

In formula (1), the parameters δd, δp and δh of butyl acetate are 15.8(MPa)^(1/2), 3.7 (MPa)^(1/2), and 6.3 (MPa)^(1/2), respectively.

According to the invention of the disclosure, at least one of themonomers (a1) shows a difference of R between the monomer (a1) and acompound in which an acid is removed from the monomer (a1) in the rangeof not less than 5.

Resin (A) preferably contains a structural unit (s).

According to the invention of the disclosure, one or more monomers (s)show the distance R in the range of 6.7 or less, preferably 6.6 or less,more preferably 6.5 or less.

At least one of the monomers (a1) showing a difference of R in the rangeof preferably not less than 2.8, more preferably not less than 3, stillmore preferably not less than 3.2, further more preferably not less than4.5.

If the resin (A) has a structural unit (a1) derived the monomer showingthe distance R within the above-mentioned range, the difference in thesolubility of resin to butyl acetate between an unexposed compositionlayer and an exposed composition layer is large at the step ofdevelopment using butyl acetate in the process of producing aphotoresist pattern. In the exposed composition layer, an acid has beenremoved from an acid-labile group of the structural unit (a1) so thatthe solubility of resin therein is decreased, resulting that the layereasily maintains its shape. In the unexposed composition layer, an acidhas not been removed so that the solubility of resin therein isincreased, resulting that the layer easily changed its shape. As aresult, a photoresist pattern with an excellent CD uniformity or smallermask error factor can be produced from the photoresist composition.

The ratio of a structural unit derived from the monomer (a1) showing thedifference of R in the range of not less than 4.5 can be not less than30% by mole with respect to all the structural units of the resin.

The ratio is more preferably not less than 65% by mole with respect toall the structural units of the resin (A), and the ratio is usually notmore than 35% by mole with respect to all the structural units of theresin.

Typical examples of the structural unit (a1) include those derived froma compound represented by formula (I). The compound can show thedifference in the range of not less than 5.

In the formula, X^(a) and X^(b) each independently an oxygen atom or asulfur atom,

W² represents a C3 to C36 alicyclic hydrocarbon group which can have asubstituent and a methylene group of which can be replaced by an oxygenatom, a sulfur atom, a carboxy group or a sulfonyl group,

R¹ represents a C1 to C8 alkyl group in which a methylene group can bereplaced by an oxygen atom or a carboxy group,

R² represents a hydrogen atom or a methyl group,

A¹ represents a single bond or a C1 to C24 divalent saturatedhydrocarbon group where a methylene group can be replaced by an oxygenatom or a carbonyl group, and

X¹ represents a group represented by formulae (X¹-1) to (X¹-4):

where * and ** represent a binding position respectively, and **represents a binding position to A¹.

X^(a) and X^(b) are preferably the same atom, more preferably an oxygenatom.

W² can have an substituent such as a hydroxy group, a C1 to C12 chainaliphatic hydrocarbon group, a C1 to C12 alkoxy group, a C2 to C13 acylgroup, a C2 to C13 acyloxy group, a C2 to C13 alkoxycarbonyl group, acyano group, a carboxyl group, a C6 to C12 aromatic hydrocarbon group orany combination of these groups.

Examples of the alicyclic hydrocarbon group represented by W² can be amonocyclic group or a polycyclic hydrocarbon group such as a condensedring, a spiro ring, or a set of rings). The methylene group of alicyclichydrocarbon group can be replaced by an oxygen atom, a sulfur atom, acarboxy group or a sulfonyl group.

Examples of the alicyclic hydrocarbon group include groups representedby formulae (w1-1) to (w1-14). Examples of the alicyclic hydrocarbongroup in which has been replaced by an oxygen atom, a sulfur atom, acarboxy group or a sulfonyl group include groups represented by formulae(w1-15) to (w1-30). The divalent alicyclic hydrocarbon group preferablyhas 3 to 18 carbon atoms. Preferred examples of the divalent alicyclichydrocarbon group include the groups represented by formulae (w1-1) to(w1-3), (w1-6), (w1-12) and (w1-14).

Examples of the chain aliphatic hydrocarbon group as the substituentinclude an alkyl group such as methyl, ethyl, propyl, n-butyl,sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl andnonyl groups. Examples of the alkoxy group as the substituent include amethoxy group, an ethoxy group, a propoxy group, a butoxy group, apentyloxy group, a hexyloxy group, an octyloxy group, a 2-ethylhexyloxygroup, a nonyloxy group, a decyloxy group, an undecyloxy group and adodecyloxy group. Examples of the acyl group as the substituent includeacetyl, propanonyl and butylyl groups.

Examples of the acyloxy group as the substituent include amethylcarbonyloxy group, an ethylcarbonyloxy group, an-propylcarbonyloxy group, an isopropylcarbonyloxy group, ann-butylcarbonyloxy group, a sec-butylcarbonyloxy group, atert-butylcarbonyloxy group, a pentylcarbonyloxy group, ahexylcarbonyloxy group, an octylcarbonyloxy group and a2-ethylhexylcarbonyloxy group.

Examples of the alkoxycarbonyl group as the substituent include amethoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group,a butoxycarbonyl group, a pentyloxycarbonyl group, a hexyloxycarbonylgroup, an octyloxycarbonyl group, a 2-ethylhexyloxycarbonyl group, anonyloxycarbonyl group, a decyloxycarbonyl group, an undecyloxycarbonylgroup and a dodecyloxycarbonyl group.

Examples of the aromatic hydrocarbon group as the substituent includephenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl groups.

Examples of the combination of these groups as the substituent includean alkoxyalkoxyalkyl group, an alkoxyacyloxy group, and a hydroxyalkylgroup.

The alicyclic hydrocarbon group represented by W² has preferably ahydroxy group, a C1 to C12 alkyl group, or a C1 to C12 hydroxyalkylgroup.

Examples of R¹ include the alkyl group as specifically mentioned above.

R¹ is preferably a C1 to C4 alkyl group, more preferably a methyl groupor an ethyl group.

Examples of the divalent saturated hydrocarbon group represented by A¹include an alkanediyl group, a divalent monocyclic or polycyclicalicyclic hydrocarbon group, and combination of these groups,specifically include linear alkanediyl groups such as a methylene group,an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diylgroup, an octane-1,8-diyl group, a nonane-1,9-diyl group, adecane-1,10-diyl group, an undecane-1,11-diyl group, adodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and heptadecane-1,17-diyl group; branchedalkanediyl groups such as an ethane-1,1-diyl group, a propane-1,1-diylgroup, a propane-1,2-diyl group, a propane-2,2-diyl group, apentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, a 2-methylbutane-1,4-diyl group;

monocyclic alicyclic hydrocarbon groups such as a cyclobutane-1,3-diylgroup, a cyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group, anda cyclooctane-1,5-diyl group; and polycyclic monocyclic alicyclichydrocarbon groups such as norbornane-1,4-diyl group,norbornane-2,5-diyl group, adamantane-1,5-diyl group, andadamantane-2,6-diyl group.

As to A¹, examples of the divalent saturated hydrocarbon group where amethylene group has been replaced by an oxygen atom or a carbonyl groupinclude a group represented by formula (a-h1):

wherein s represents an integer of 0 to 2, A¹⁰ in occurrence representsrepresents a C1 to C5 divalent aliphatic hydrocarbon group, X¹⁰ inoccurrence represents a single bond or a C1 to C5 divalent aliphatichydrocarbon group, and X¹⁰ independently represent —O—, —CO—, —CO—O— or—O—CO—.

The divalent aliphatic hydrocarbon group represented by A¹⁰ or A¹¹ ispreferably an alkanediyl group which can be a linear or branched one.Examples of the divalent aliphatic hydrocarbon group represented by A¹⁰include a methylene group, an ethylene group, a 1,2-propanediyl group, a1,3-propanediyl group, a 1,4-butanediyl group, a 1,5-pentanediyl groupand 1,3-pentanediyl group, preferably a methylene group and an ethylenegroup. Specific examples of the group represented by formula (a-h1)include groups as shown below.

In each formula, * represents a binding position.

A¹ is preferably a single bond or a group represented by formula (a-h1),more preferably a single bond.

Specific examples of the compound represented by formula (I) includegroups represented by the following groups and those in which a methylgroup corresponding to R² has been replaced by a hydrogen atom.

The ratio of a structural unit derived from the monomer represented byformula (I), which structural unit is sometimes referred to as“structural unit (I)”, is preferably from 1 to 30% by mole, morepreferably from 2 to 30% by mole, still more preferably from 3 to 15% bymole, further still more preferably from 3 to 10% by mole, with respectto all the structural units of the resin (A).

<Structural Unit (a1) Other than the Structural Unit (I)>

In Resin (A), the acid-labile group of the structural unit (a1) otherthan the structural unit (I) is preferably one represented by formula(1) or formula (2).

In the formula, R^(a1) to R^(a3) independently represent a C1 to C8alkyl group, a C3 to C20 alicyclic hydrocarbon group or combinationthereof, or R^(a1) and R^(a2) can be bonded together with a carbon atombonded thereto to form a C3 to C20 divalent alicyclic hydrocarbon group,

na represents an integer of 0 or 1, and * represents a binding position.

In the formula, R^(a1′) and R^(a2′) independently represent a hydrogenatom or a C1 to C12 hydrocarbon group, R^(3′) represents a C1 to C20hydrocarbon group, or R^(a2′) and R^(a3′) can be bonded together with acarbon atom and X bonded thereto to form a divalent C3 to C20heterocyclic group, and a methylene group contained in the hydrocarbongroup or the divalent heterocyclic group can be replaced by an oxygenatom or sulfur atom, X represents —O— or —S—, and * represents a bindingposition.

Examples of the alkyl group for R^(a1) to R^(a3) include methyl, ethyl,propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group for R^(a1) to R^(a3) includemonocyclic groups such as a cycloalkyl group, i.e., cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl groups, and polycyclic hydrocarbongroups such as decahydronaphtyl, adamantyl and norbornyl groups as wellas groups below. * represents a binding position.

The alicyclic hydrocarbon group of R^(a1) to R^(a3) preferably has 3 to16 carbon atoms.

Examples of groups combining the alkyl group and the alicyclichydrocarbon group include methylcyclohexyl, dimethylcyclohexyl,methylnorbornyl, cyclohexylmethyl, adamantylmethyl and norbornyletylgroups.

na is preferably an integer of 0.

When R^(a1) and R^(a2) are bonded together to form a divalent alicyclichydrocarbon group, examples of the group represented by—C(R^(a1))(R^(a2))(R^(a3)) include groups below. The divalent alicyclichydrocarbon group preferably has 3 to 12 carbon atoms. * represent abinding position to —O—.

Specific examples of the group represented by formula (1) include1,1-dialkylalkoxycarbonyl group (a group represented by formula (1) inwhich R^(a1) to R^(a3) are alkyl groups, preferably tert-butoxycarbonylgroup), 2-alkyladamantane-2-yloxycarbonyl group (a group represented byformula (1) in which R^(a1), R^(a2) and a carbon atom form adamantylgroup, and R^(a3) is alkyl group), and1-(adamantane-1-yl)-1-alkylalkoxycarbonyl group (a group represented byformula (1) in which R^(a1) and R^(a2) are alkyl group, and R^(a3) isadamantyl group).

The hydrocarbon group for R^(a1′) to R^(a3′) includes an alkyl group, analicyclic hydrocarbon group, an aromatic hydrocarbon group and acombination thereof.

Examples of the alkyl group and the alicyclic hydrocarbon group are thesame examples as described above.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the divalent heterocyclic group formed by binding withR^(a2′) and R^(a3′) include groups below. * represents a bindingposition.

At least one of R^(a1′) and R^(a2′) is preferably a hydrogen atom.

Specific examples of the group represented by formula (2) include agroup below. * represents a binding position.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylene unsaturated bond, and more preferably a (meth)acrylicmonomer having an acid-labile group.

Among the (meth)acrylic monomer having an acid-labile group, a monomerhaving a C5 to C20 alicyclic hydrocarbon group is preferred. When aresin (A) having a structural unit derived from a monomer (a1) having abulky structure such as the alicyclic hydrocarbon group is used for aphotoresist composition, the photoresist composition having excellentresolution tends to be obtained.

Examples of a structural unit derived from the (meth)acrylic monomerhaving the group represented by formula (1) preferably includestructural units represented by formula (a1-0), formula (a1-1) andformula (a1-2) below. These may be used as one kind of the structuralunit or as a combination of two or more kinds of the structural units.The structural unit represented by formula (a1-0), the structural unitrepresented by formula (a1-1) and a structural unit represented byformula (a1-2) are sometimes referred to as “structural unit (a1-0)”,“structural unit (a1-1)” and “structural unit (a1-2)”), respectively,and monomers deriving the structural unit (a1-0), the structural unit(a1-1) and the structural unit (a1-2) are sometimes referred to as“monomer (a1-0)”, “monomer (a1-1)” and “monomer (a1-2)”), respectively.

In these formulae, L^(a01), L^(a1) and L^(a2) independently represent—O— or *—O—(CH₂)_(k1)—CO—O— where k1 represents an integer of 1 to 7and * represents a binding position to —CO—,

R^(a01), R^(a4) and R^(a5) independently represent a hydrogen atom or amethyl group,

R^(a02), R^(a03) and R^(a04) independently represent a C1 to C8 alkylgroup, a C3 to C18 alicyclic hydrocarbon group or combination thereof,

R^(a6) and R^(a7) independently represent a C1 to C8 alkyl group, a C3to C18 alicyclic hydrocarbon group or a combination thereof,

R^(a6) and R^(a7) independently represent a C1 to C8 alkyl group, a C3to C18 alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

L^(a01), L^(a1) and L^(a2) is preferably an —O— or *—O—(CH₂)_(k01)—CO—O—in which k01 is preferably an integer of 1 to 4, more preferably aninteger of 1, still more preferably an —O—.

R^(a4) and R^(a5) are preferably a methyl group.

Examples of the alkyl group, an alicyclic hydrocarbon group andcombination thereof for R^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) arethe same examples as the group described in R^(a1) to R^(a3) in formula(1).

The alkyl group for R^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) ispreferably a C1 to C6 alkyl group.

The alicyclic hydrocarbon group for R^(a02), R^(a03), R^(a04), R^(a6)and R^(a7) is preferably a C3 to C8 alicyclic hydrocarbon group, morepreferably a C3 to C6 alicyclic hydrocarbon group.

The group formed by combining the alkyl group and the alicyclichydrocarbon group has preferably 18 or less of carbon atom. Examples ofthose groups include methylcyclohexyl, dimethylcyclohexyl,methylnorbornyl, methyladamantyl, cyclohexylmethyl, methylcyclohexylmethyl, adamantylmethyl and norbornylmethyl groups.

Each of R^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) is preferably a C1to C6 alkyl group, more preferably a methyl group or an ethyl group.

R^(a04) is preferably a C1 to C6 alkyl group or a C5 to C12 alicyclichydrocarbon group, more preferably a methyl, ethyl, cyclohexyl oradamantyl group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1, and more preferably 1.

Examples of the structural unit (a1-0) preferably include thoserepresented by formula (a1-0-1) to formula (a1-0-12) and these in whicha methyl group corresponding to R^(a01) has been replaced by a hydrogenatom, and more preferably those represented by formula (a1-0-1) toformula (a1-0-6), formula (a1-0-8) and formula (a1-0-9) below.

Examples of the structural unit (a1-1) include those derived frommonomers described in JP 2010-204646A1. Among them, preferred are thestructural units represented by formula (a1-1-1) to formula (a1-1-4).

Examples of the structural unit (a1-2) include the structural unitsrepresented by formula (a1-2-1) to formula (a1-2-6), and preferablythose represented by formula (a1-2-2) and formula (a1-2-5).

Specific examples of the structural unit (a1-2) include the structuralunits represented by formulae (a1-0-1) to (a1-0-12), (a1-1-1) to(a1-1-4) and (a1-2-1) to (a1-2-6) in which a methyl group correspondingto R^(a01), R^(a4) or R^(a5) has been replaced by a hydrogen atom.

When Resin (A) has the structural unit (a1-0), the structural unit(a1-1) and/or the structural unit (a1-2), the total proportion thereofis generally 10 to 95% by mole, preferably 15 to 90% by mole, morepreferably 20 to 85% by mole, still more preferably 20 to 50% by mole,with respect to all of the structural units in the resin.

Examples of the structural unit (a1) further include the following ones.

When Resin (A) has any one of the structural units represented byformula (a1-3-1) to formula (a1-3-7), the total proportion of thesestructural units is generally 10 to 95% by mole, preferably 15 to 90% bymole, more preferably 20 to 85% by mole, still more preferably 20 to 50%by mole, with respect to all the structural units of the resin.

Examples of a structural unit having an acid-labile group, which isderived from a (meth)acrylic monomer include a structural unitrepresented by formula (a1-5). Such structural unit is sometimesreferred to as “structural unit (a1-5)”.

In the formula, Rae represents a hydrogen atom, a halogen atom or a C1to C6 alkyl group which can have a halogen atom,

Z^(a1) represents a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-, where h3represents an integer of 1 to 4, L⁵⁴ represents —O— or —S— and *represents a binding position to L⁵¹,

L⁵¹, L⁵² and L⁵³ independently represent —O— or —S—,

s1 represents an integer of 1 to 3, and

s1′ represents an integer of 0 to 3.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms, and preferably a fluorine atom.

Examples of the alkyl group which can have a halogen atom includemethyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, fluoromethyland trifluoromethyl groups.

In formula (a1-5), Rae is preferably a hydrogen atom, a methyl group ortrifluoromethyl group. L⁵¹ is preferably —O—. L⁵² and L⁵³ areindependently preferably —O— or —S—, and more preferably one is —O— andanother is —S—.

s1 is preferably 1.

s1′ is preferably an integer of 0 to 2. Z^(a1) is preferably a singlebond or *—CH₂—CO—O— where * represents a binding position to L⁵¹.

Examples of a monomer from which the structural unit (a1-5) is derivedinclude a monomer described in JP 2010-61117A. Among them, the monomersare preferably monomers represented by formula (a1-5-1) to formula(a1-5-4), and more preferably monomers represented by formula (a1-5-1)to formula (a1-5-2) below.

When Resin (A) has the structural unit (a1-5), the proportion thereof isgenerally 1% by mole to 50% by mole, preferably 3% by mole to 45% bymole, and more preferably 5% by mole to 40% by mole, with respect to thetotal structural units (100% by mole) constituting Resin (A).

Examples of a structural unit (a1) having a group represented by formula(2) include a structural unit represented by formula (a1-4). Thestructural unit is sometimes referred to as “structural unit (a1-4)”.

In the formula, R^(a32) represents a hydrogen atom, a halogen atom or aC1 to C6 alkyl group which can have a halogen atom,

R^(a33) in each occurrence independently represent a halogen atom, ahydroxy group, a C1 to C6 alkyl group, a C1 to C6 alkoxy group, a C2 toC4 acyl group, a C2 to C4 acyloxy group, an acryloyloxy group ormethacryloyloxy group, la represents an integer 0 to 4, R^(a34) andR^(a35) independently represent a hydrogen atom or a C1 to C12hydrocarbon group; and R^(a36) represents a C1 to C20 hydrocarbon group,or R^(a35) and R^(a36) can be bonded together with a C—O bonded theretoto form a C3 to C20 divalent heterocyclic group, and a methylene groupcontained in the hydrocarbon group or the divalent heterocyclic groupcan be replaced by an oxygen atom or sulfur atom.

Examples of the alkyl group for R^(a32) and R^(a33) include methyl,ethyl, propyl, isopropyl, butyl, pentyl and hexyl groups. The alkylgroup is preferably a C1 to C4 alkyl group, and more preferably a methylgroup or an ethyl group, and still more preferably a methyl group.

Examples of the halogen atom for R^(a32) and R^(a33) include fluorine,chlorine, bromine and iodine atoms.

Examples of the alkyl group which can have a halogen atom includetrifluoromethyl, difluoromethyl, methyl, perfluoromethyl,1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl,1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

Examples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, and hexyloxy groups. The alkoxy group is preferably a C1 toC4 alkoxy group, more preferably a methoxy group or an ethoxy group, andstill more preferably a methoxy group.

Examples of the acyl group include acetyl, propanonyl and butylylgroups.

Examples of the acyloxy group include acetyloxy, propanonyloxy andbutylyloxy groups.

Examples of the hydrocarbon group for R^(a34) and R^(a35) are the sameexamples as described in R^(a1′) to R^(a2′) in formula (2).

Examples of hydrocarbon group for R^(a36) include a C1 to C18 alkylgroup, a C3 to C18 alicyclic hydrocarbon group, a C6 to C18 aromatichydrocarbon group and a combination thereof.

In formula (a1-4), R^(a32) is preferably a hydrogen atom.

R^(a33) is preferably a C1 to C4 alkoxy group, more preferably a methoxygroup or an ethoxy group, and still more preferably a methoxy group.

la is preferably 0 or 1, and more preferably 0.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a C1 to C12 hydrocarbon group, and more preferablya methyl group or an ethyl group.

The hydrocarbon group for R^(a36) is preferably a C1 to C18 alkyl group,a C3 to C18 alicyclic hydrocarbon group, a C6 to C18 aromatichydrocarbon group and a combination thereof, and more preferably a C1 toC18 alkyl group, a C3 to C18 alicyclic hydrocarbon group or a C7 to C18aralkyl group. Each of the alkyl group and the alicyclic hydrocarbongroup for R^(a36) is preferably not substituted. When the aromatichydrocarbon group of R^(a36) has a substituent, the substituent ispreferably a C6 to C10 aryloxy group. Examples of the structural unit(a1-4) include the following ones.

When Resin (A) contains the structural unit (a1), the proportion thereofis generally 10% by mole to 95% by mole, preferably 15% by mole to 90%by mole, more preferably 20% by mole to 85% by mole, still morepreferably 20% by mole to 50% by mole, with respect to the totalstructural units constituting Resin (A) (100% by mole).

Resin (A) preferably has the structural unit (I) and at least one of thestructural unit (a1-1) and the structural unit (a1-2). More preferablyResin (A) has both the structural unit (I) and the structural unit(a1-2), or all of the structural unit (I), the structural unit (a1-1)and the structural unit (a1-2).

<Structural Unit (s)>

The structural unit (s) is derived from a monomer having no acid-labilegroup, which monomer is sometimes referred to as “monomer (s)”.

For the monomer (s), a known monomer having no acid-labile group can beused.

As the structural unit (s), preferred is a structural unit having ahydroxy group or a lactone ring but having no acid-labile group. Whenthe photoresist composition contains a resin which has a structural unit(s) having a hydroxy group (such structural unit is sometimes referredto as “structural unit (a2)”) and/or a structural unit (s) having alactone ring (such structural unit is sometimes referred to as“structural unit (a3)”), the adhesiveness of photoresist obtainedtherefrom to a substrate and resolution of photoresist pattern tend tobe improved.

<Structural Unit (a2)>

A hydroxy group which the structural unit (a2) has can be an alcoholichydroxy group or a phenolic hydroxy group.

When KrF excimer laser lithography (248 nm), or high-energy irradiationsuch as electron beam or EUV (extreme ultraviolet) is used for thephotoresist composition, the structural unit having a phenolic hydroxygroup is preferably used as structural unit (a2).

When ArF excimer laser lithography (193 nm) is used, the structural unithaving an alcoholic hydroxy group is preferably used as structural unit(a2), and the structural represented by formula (a2-1) is morepreferred. The structural unit (a2) can be used as one kind of thestructural unit or as a combination of two or more kinds of thestructural units.

When Resin (A) has the structural unit (a2) having the phenolic hydroxygroup, the proportion thereof is generally 5% by mole to 95% by mole,preferably 10% by mole to 80% by mole, more preferably 15% by mole to80% by mole, still more preferably 20% by mole to 50% by mole, withrespect to the total structural units (100% by mole) constituting Resin(A). Examples of the structural unit (a2) having alcoholic hydroxy groupinclude the structural unit represented by formula (a2-1) (which issometimes referred to as “structural unit (a2-1)”).

In the formula, L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—, k2represents an integer of 1 to 7, * represents a binding position to—CO—, R^(a14) represents a hydrogen atom or a methyl group, R^(a15) andR^(a16) each independently represent a hydrogen atom, a methyl group ora hydroxy group, and o1 represents an integer of 0 to 10.

In formula (a2-1), L^(a3) is preferably —O—, —O—(CH₂)_(f1)—CO—O—, heref1 represents an integer of 1 to 4, and more preferably —O—. R^(a14) ispreferably a methyl group. R^(a15) is preferably a hydrogen atom.R^(a16) is preferably a hydrogen atom or a hydroxy group, morepreferably a hydroxy group. o1 is preferably an integer of 0 to 3, andmore preferably an integer of 0 or 1.

Preferred examples of the structural unit (a2-1) include thoserepresented by formula (a2-1-1) to formula (a2-1-3), and more preferablythose represented by formula (a2-1-1) to formula (a2-1-2).

Examples of the structural unit (a2-1) also include those represented byformulae (a2-1-1) to (a2-1-3) in which a methyl group has been replacedby a hydrogen atom.

When Resin (A) has the structural unit (a2-1), the proportion thereof isgenerally 1% by mole to 45% by mole, preferably 1% by mole to 40% bymole, more preferably 1% by mole to 35% by mole, and still morepreferably 2% by mole to 20% by mole, with respect to the totalstructural units (100% by mole) constituting Resin (A).

<Structural unit (a3)>

The lactone ring included in the structural unit (a3) can be amonocyclic compound such as β-propiolactone, γ-butyrolactone,δ-valerolactone, or a condensed ring of monocyclic lactone ring withanother ring. Examples of the lactone ring preferably includeγ-butyrolactone or bridged ring with γ-butyrolactone.

Examples of the structural unit (a3) include structural unitsrepresented by any of formula (a3-1), formula (a3-2), formula (a3-3) andformula (a3-4). These structural units may be used as one kind of thestructural unit or as a combination of two or more kind of thestructural units.

In the formula, L^(a4), Las and Lab each independently represent *—O— or*—O— (CH₂)_(k3)—CO—O—, k3 represents an integer of 1 to 7, * representsa binding position to a carbonyl group,

L^(a7) represents —O—, *—O-L^(a8)-O—, —O-L^(a8)-CO—O—,*—O-L^(a8)-CO—O-L^(a9)-CO—O— or *—O-L^(a8)-O—CO-L^(a9)-O— where *represents a binding position to a carbonyl group, L^(a8) and L^(a9)each independently represent a C1 to C6 alkanediyl group, and R^(a18),R^(a19) and R^(a20) each independently represent a hydrogen atom or amethyl group, R^(a24) represents a hydrogen atom, a halogen atom or a C1to C6 alkyl group which can have a halogen atom,

R^(a21) in each occurrence represents a C1 to C4 aliphatic hydrocarbongroup, R^(a22), R^(a23) and R^(a25) in each occurrence represent acarboxy group, a cyano group or a C1 to C4 aliphatic hydrocarbon group,

p1 represents an integer of 0 to 5, q1 represents an integer of 0 to 3,r1 represents an integer of 0 to 3, and w1 represents an integer of 0 to8.

Examples of the aliphatic hydrocarbon group for R^(a21), R^(a2) andR^(a3) include an alkyl group such as methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups.

Examples of a halogen atom for R²⁴ include fluorine, chlorine, bromineand iodine atoms.

Examples of an alkyl group for R²⁴ include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups,preferably methyl and ethyl groups.

Examples of the alkyl group having a halogen atom for R^(a24) includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl andtriiodomethyl groups.

Examples of an alkanediyl group for L^(a8) and L^(a9) include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl, pentane-1,4-diyl and2-methylbutane-1,4-diyl groups.

In formulae (a3-1) to (a3-3), L^(a4) to L^(a6) is independentlypreferably —O—, *—O—(CH₂)_(k3′)—CO—O—, here k3′ represents an integer of1 to 4, more preferably —O— or *—O—CH₂—CO—O—, and still more preferably—O—.

R^(a18) to R^(a21) are preferably a methyl group.

In formula (a3-4), R²⁴ is preferably a hydrogen atom or a C1 to C4 alkylgroup, more preferably a hydrogen atom, a methyl group or an ethylgroup, and still preferably a hydrogen atom or a methyl group. L^(a7) ispreferably —O—, or *—O-L^(a8)-CO—O—, more preferably —O—, *—O—CH₂—CO—O—,or *—O— (CH₂)₂—CO—O—.

In formulae (a3-1), (a3-2) and (a3-4), R^(a2), R^(a23) and R^(a25) areindependently preferably a carboxy group, a cyano group or a methylgroup.

In formulae (a3-1) to (a3-4), p1, q1, r1 and w1 are independentlypreferably an integer of 0 to 2, and more preferably 0 or 1.

The structural unit represented by formula (a3-4) is preferably onerepresented by formula (a3-4)′.

In the formula, R^(a24) and L^(a7) are as defined above.

Examples of the monomer from which the structural unit (a3) is derivedinclude monomers described in JP 2010-204646A, monomers described inJP2000-122294A and monomers described in JP2012-41274A. The structuralunits are preferably structural units represented by the followingformulae, more preferably a structural unit represented by formula(a3-1-1), (a3-2-3), (a3-4-1) to (a3-4-12), and still more preferably astructural unit represented by any one of formulae (a3-4-1) to (a3-4-6).

Examples of the structural unit (a3) also include those represented byformulae (a3-1-1), (a3-1-2), (a3-2-1) to (a3-1-4) and (a3-4-1) to(a3-4-12) in which a methyl group has been replaced by a hydrogen atom.

When Resin (A) has the structural unit (a3), the total proportionthereof is preferably 5% by mole to 70% by mole, more preferably 10% bymole to 65% by mole, still more preferably 10% by mole to 60% by mole,with respect to the total structural units (100% by mole) constitutingResin (A).

The proportion of each structural unit represented by formula (a3-1),formula (a3-2), formula (a3-3) and formula (a3-4) is preferably 5% bymole to 60% by mole, more preferably 5% by mole to 50% by mole, stillmore preferably 10% by mole to 50% by mole, with respect to the totalstructural units (100% by mole) constituting Resin (A).

<Structural Unit (t)>

Examples of the structural unit further include a structural unit whichmay have a halogen atom (which is sometimes referred to as “structuralunit (a4)”), and a structural unit having a non-leaving hydrocarbongroup (which is sometimes referred to as “structural unit (a5)”).Hereinafter, the structural units (a4) and (a5) are collectivelyreferred to as “structural unit (t)”.

<Structural Unit (a4)>

Examples of the structural unit (a4) include the structural unitsrepresented by formula (a4-0).

In the formula, R⁵ represents a hydrogen atom or a methyl group,

L⁵ represent a single bond or a C1 to C4 saturated aliphatic hydrocarbongroup, L³ represents a C1 to C8 perfluoroalkanediyl group or a C3 to C12perfluorocycloalkanediyl group, and R⁶ represents a hydrogen atom or afluorine atom.

Examples of the saturated aliphatic hydrocarbon group for L⁵ include aliner alkanediyl group such as methylene, ethylene, propane-1,3-diyl,butane-1,4-diyl, and a branched alkanediyl group such asethane-1,1-diyl, propane-1,2-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl and 2-methylpropane-1,2-diyl groups.

Examples of the perfluoroalkanediyl group for L³ includedifluoromethylene, perfluoroethylene, perfluoroethylmethylene,perfluoropropane-1,3-diyl, perfluoropropane-1,2-diyl,perfluoropropane-2,2-diyl, perfluorobutane-1,4-diyl,perfluorobutane-2,2-diyl, perfluorobutane-1,2-diyl,perfluoropentane-1,5-diyl, perfluoropentane-2,2-diyl,perfluoropentane-3,3-diyl, perfluorohexane-1,6-diyl,perfluorohexane-2,2-diyl, perfluorohexane-3,3-diyl,perfluoroheptane-1,7-diyl, perfluoroheptane-2,2-diyl,perfluoroheptane-3,4-diyl, perfluoroheptane-4,4-diyl,perfluorooctan-1,8-diyl, perfluorooctan-2,2-diyl,perfluorooctan-3,3-diyl and perfluorooctan-4,4-diyl groups.

Examples of the perfluorocycloalkanediyl group for L³ includeperfluorocyclohexanediyl, perfluorocyclopentanediyl,perfluorocycloheptanediyl and perfluoroadamantanediyl groups.

L⁵ is preferably a single bond, a methylene or an ethylene group, andmore preferably a single bond or a methylene group.

L³ is preferably a C1 to C6 perfluoroalkanediyl group, more preferably aC1 to C3 perfluoroalkanediyl group.

Examples of the structural unit (a4-0) include structural unitsrepresented by formula (a4-0-1) to formula (a4-0-16).

Examples of the structural unit (a4) also include those represented byformulae (a4-0-1) to (a4-0-16) in which a methyl group has been replacedby a hydrogen atom.

Examples of the structural unit (a4) include the structural unitsrepresented by formula (a4-1).

In the formula, R^(a41) represents a hydrogen atom or a methyl group,

R^(a42) represents an optionally substituted C1 to C20 hydrocarbon groupwhere a methylene group can be replaced by an oxygen atom or a carbonylgroup, and

A^(a41) represents an optionally substituted C1 to C6 alkanediyl groupor a group represented by formula (a-g1):

wherein s represents 0 or 1, A^(a42) and A^(a44) independently representan optionally substituted C1 to C5 divalent aliphatic hydrocarbon group,A^(a43) in occurrence represents a single bond or an optionallysubstituted C1 to C5 divalent aliphatic hydrocarbon group, and X^(a41)and X^(a42) independently represent —O—, —CO—, —CO—O— or —O—CO—,provided that the total number of the carbon atoms contained in thegroup of A^(a42), A^(a43), A^(a44), X^(a41) and X^(a42) is 7 or less,and at least one of A^(a4) and R^(a42) has a halogen atom as asubstituent, and * and ** represent a binding position, and * representsa binding position to —O—CO—R^(a42).

The hydrocarbon group for R^(a42) includes a chain aliphatic hydrocarbongroup, a cyclic aliphatic hydrocarbon group, an aromatic hydrocarbongroup and a combination thereof.

The hydrocarbon group may have a carbon-carbon unsaturated bond, ispreferably a chain aliphatic hydrocarbon group, a cyclic saturatedaliphatic hydrocarbon group and a combination thereof.

The saturated aliphatic hydrocarbon group is preferably a liner or abranched alkyl group, a monocyclic or a polycyclic alicyclic hydrocarbongroup, and an aliphatic hydrocarbon group combining an alkyl group withan alicyclic hydrocarbon group.

Examples of the chain aliphatic hydrocarbon group include an alkyl groupsuch as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, n-decyl, n-dodecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl andn-octadecyl groups. Examples of the cyclic aliphatic hydrocarbon groupinclude a monocyclic hydrocarbon group, i.e., cycloalkyl group such ascyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl groups; and polycyclichydrocarbon groups such as decahydronaphtyl, adamantyl and norbornylgroups as well as groups below. * represents a binding position.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, biphenyl, phenanthryl and fluorenyl groups.

Examples of the substituent of R^(a42) include a halogen atom or a grouprepresented by formula (a-g3).*—X^(a43)-A^(a45)  (a-g3)

In the formula, X^(a43) represent an oxygen atom, a carbonyl group, acarbonyloxy group or an oxycarbonyl group,

A^(a45) represents a C1 to C17 aliphatic hydrocarbon group that has ahalogen atom, and * represents a binding position.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atom, and a fluorine atom is preferred.

Examples of the aliphatic hydrocarbon group for A^(a45) are the sameexamples as the group of R^(a42).

R^(a42) is preferably an aliphatic hydrocarbon group which can have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or an aliphatic hydrocarbon group having the group represented byformula (a-g3).

When R^(a42) is an aliphatic hydrocarbon group having a halogen atom, analiphatic hydrocarbon group having a fluorine atom is preferred, aperfluoroalkyl group or a perfulorocycloalkyl group are more preferred,a C1 to C6 perfluoroalkyl group is still more preferred, a C1 to C3perfluoroalkyl group is particularly preferred.

Examples of the perfluoroalkyl group include perfluoromethyl,perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl,perfluorohexyl, perfluoroheptyl and perfluorooctyl groups. Examples ofthe perfluorocycloalkyl group include perfluorocyclohexyl group.

When R^(a42) is an aliphatic hydrocarbon group having the grouprepresented by formula (a-g3), the total number of the carbon atomscontained in the aliphatic hydrocarbon group including the grouprepresented by formula (a-g3) is preferably 15 or less, more preferably12 or less. The number of the group represented by formula (a-g3) ispreferably one when the group represented by formula (a-g3) is thesubstituent.

Examples of preferred structure represented by formula (a-g3) includethe following ones.

Examples of the alkanediyl group for A^(a41) include a liner alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as propane-1,2-diyl, butan-1,3-diyl,2-methylpropane-1,2-diyl, 1-methylpropane-1,4-diyl,2-methylbutane-1,4-diyl groups.

Examples of the substituent of the alkanediyl group of A^(a41) include ahydroxy group and a C1 to C6 alkoxy group.

Examples of the substituent of the alkanediyl of A^(a41) include ahydroxy group and a C1 to C6 alkoxy group.

A^(a41) is preferably a C1 to C4 alkanediyl group, more preferably a C2to C4 alkanediyl group, and still more preferably an ethylene group.

In the group represented by formula (a-g1) (which is sometimes referredto as “group (a-g1)”), the aliphatic hydrocarbon group for A^(a42),A^(a43) and A^(a44) may have a carbon-carbon unsaturated bond, ispreferably a saturated aliphatic hydrocarbon group.

The saturated aliphatic hydrocarbon group is preferably a liner or abranched alkyl group, a monocyclic or a polycyclic alicyclic hydrocarbongroup, and an aliphatic hydrocarbon group combining an alkyl group withan alicyclic hydrocarbon group.

Examples of the aliphatic hydrocarbon group for A^(a42), A^(a43) andA^(a44) include methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl,butane-1,4-diyl, l-methylpropane-1,3-diyl, 2-methylpropane-1,3-diyl and2-methylpropane-1,2-diyl groups.

Examples of the substituent of the aliphatic hydrocarbon group ofA^(a42), A^(a43) and A^(a44) include a hydroxy group and a C1 to C6alkoxy group.

s is preferably 0.

Examples of the group (a-g1) in which X^(a42) represents an oxygen atom,a carbonyl group, a carbonyloxy group or an oxycarbonyl group includethe following ones. In the formula, * and ** each represent a bindingposition, and ** represents a binding position to —O—CO—R^(a42).

Examples of the structural unit represented by formula (a4-1) includestructural units represented by the formulae and those represented bythe formulae in which a methyl group corresponding to R^(a41) has beenreplaced by a hydrogen atom.

Examples of the structural unit (a4) further include a structural unitpresented by formula (a4-4):

wherein R^(f21) represents a hydrogen atom or a methyl group,

A^(f21) represents —(CH₂)_(j1)—, —(CH₂)_(j2)—O— (CH₂)_(j3)— or—(CH₂)_(j4)—CO—O—(CH₂)_(j5)—,

j1 to j5 independently represents an integer of 1 to 6, and

R^(f22) represents a C1 to C10 hydrocarbon group having a fluorine atom.

Examples of the hydrocarbon group having a fluorine atom for R^(f22)include a C1 to C10 alkyl group having a fluorine atom and a C3 to C10alicyclic hydrocarbon group having a fluorine atom.

Specific examples of R^(f22) include a difluoromethyl group, atrifluoromethyl group, 1,1-difluoroethyl group, 2,2-difluoroethyl group,a 2,2,2-trifluoroethyl group, a perfluoroethyl group, a1,1,2,2-tetrafluoropropyl group, a 1,1,2,2,3,3-hexafluoropropyl group, aperfluoroethylmethyl group 1-(trifluoromethyl)-1,2,2,2-tetrafluoroethylgroup, 1-(trifluoromethyl)-2,2,2-trifluoroethyl group, a perfluoroethylgroup, 1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, a perfluorobuthyl group,1,1-bis(trifluoro) methyl-2,2,2-trifluoroethyl group,2-(perfluoropropyl) ethyl group, 1,1,2,2,3,3,4,4-octafluoropentyl group,a perfluoropentyl group, 1,1,2,2,3,3,4,4,5,5-fluorodecapentyl group,1,1-(trifluoromethyl)-2,2,3,3,3-pentafluoropropyl group,2-(perfluorobuthyl) ethyl group, 1,1,2,2,3,3,4,4,5,5-decafluorohexylgroup, a 1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl group,diperfluoropentylmethyl group, a perfluorohexyl group, aperfluorocyclohexyl group and a perfluoroadamantyl group.

R^(f22) is preferably a C1 to C10 alkyl group having a fluorine atom ora C3 to C10 alicyclic hydrocarbon group having a fluorine atom, morepreferably a C1 to C10 alkyl group having a fluorine atom, and stillmore preferably a C1 to C6 alkyl group having a fluorine atom.

In the formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, morepreferably a methylene group or an ethylene group, and still morepreferably a methylene group.

Examples of the structural unit represented by formula (a4-4) includethe following ones and those represented by the following formulae inwhich a methyl group corresponding to R^(f21) has been replaced by ahydrogen atom.

When Resin (A) has the structural unit (a4), the proportion thereof ispreferably 1 to 20% by mole, more preferably 2 to 15% by mole, stillmore preferably 3 to 10% by mole, with respect to the total structuralunits (100% by mole) of Resin (A).

<Structural Unit (a5)>

Examples of the non-leaving hydrocarbon group in the structural unit(a5) include a chain, branched or cyclic hydrocarbon group. Among them,the structural unit (a5) is preferably a structural unit containing analicyclic hydrocarbon group.

The structural unit (a5) is, for example, a structural unit representedby formula (a5-1):

wherein R51 represents a hydrogen atom or a methyl group,

R⁵² represents a C3 to C18 alicyclic hydrocarbon group where a hydrogenatom can be replaced by a C1 to C8 aliphatic hydrocarbon group or ahydroxy group, provided that a hydrogen atom contained in the carbonatom bonded to L⁵⁵ is not replaced by the C1 to C8 aliphatic hydrocarbongroup, and L⁵⁵ represents a single bond or a C1 to C18 divalentsaturated hydrocarbon group where a methylene group can be replaced byan oxygen atom or a carbonyl group.

Examples of the alicyclic hydrocarbon group of R⁵² include a monocyclicgroup or polycyclic group. Examples of the monocyclic alicyclichydrocarbon group include cyclopropyl, cyclobutyl, cyclopentyl andcyclohexyl groups. Examples of the polycyclic hydrocarbon group includeadamantyl and norbornyl groups.

Examples of the C1 to C8 aliphatic hydrocarbon group include an alkylgroup such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octylgroups.

Examples of the alicyclic hydrocarbon group having a substituent include3-hydroxyadamantyl and 3-methyladamantyl.

R⁵² is preferably an unsubstituted C3 to C18 alicyclic hydrocarbongroup, and more preferably adamantyl, norbornyl and cyclohexyl groups.

Examples of the divalent saturated hydrocarbon group of L⁵⁵ include adivalent aliphatic saturated hydrocarbon group and a divalent alicyclicsaturated hydrocarbon group, and a divalent aliphatic saturatedhydrocarbon group is preferred.

Examples of the divalent aliphatic saturated hydrocarbon group includean alkanediyl group such as methylene, ethylene, propanediyl, butanediyland pentanediyl groups.

Examples of the divalent alicyclic saturated hydrocarbon group include amonocyclic group and a polycyclic group. Examples of the monocyclicalicyclic saturated hydrocarbon groups include cycloalkanediyl such ascyclopentanediyl and cyclohexanediyl groups. Examples of the polycyclicsaturated hydrocarbon groups include adamantanediyl and norbornanediylgroups.

Examples of the saturated hydrocarbon group in which a methylene grouphas been replaced by an oxygen atom or a carbonyl group include groupsrepresented by formula (L1-1) to formula (L1-4). In the formula (L1-1)to formula (L1-4), * represents a binding position to an oxygen atom.

In the formula, X^(X1) represents an oxycarbonyl group or a carbonyloxygroup, L^(X1) represents a C1 to C16 divalent saturated aliphatichydrocarbon group, L^(X2) represents a single bond or a C₁ to C₁₅divalent saturated hydrocarbon group, provided that the total number ofthe carbon atoms contained in the group of L^(X1) and L^(X2) is 16 orless;

L^(X3) represents a single bond or a C1 to C17 divalent saturatedaliphatic hydrocarbon group, L⁴ represents a single bond or a C1 to C16divalent saturated hydrocarbon group, provided that the total number ofthe carbon atoms contained in the group of L^(X3) and L^(X4) is 17 orless;

L^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L^(X6) and L^(X7) independently represent a single bond or a C₁ to C₁₄divalent saturated hydrocarbon group, provided that the total number ofthe carbon atoms contained in the group of L^(X5), L^(X6) and L^(X7) is15 or less, L^(X8) and L^(X9) independently represent a single bond or aC1 to C12 divalent saturated hydrocarbon group, W^(X1) represents a C₃to C₁₅ divalent saturated alicyclic hydrocarbon group, provided that thetotal number of the carbon atoms contained in the group of L^(X8),L^(X9) and W^(X1) is 15 or less.

L^(X1) is preferably a C1 to C8 divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an ethylene group.

L^(X2) is preferably a single bond or a C1 to C8 divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond.

L^(X3) is preferably a C1 to C8 divalent saturated aliphatic hydrocarbongroup.

L^(X4) is preferably a single bond or a C1 to C8 divalent saturatedaliphatic hydrocarbon group.

L^(X5) is preferably a C1 to C8 divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an ethylene group.

L^(X6) is preferably a single bond or a C1 to C8 divalent saturatedaliphatic hydrocarbon group, and more preferably a methylene group or anethylene group. L^(X7) is preferably a single bond or a C1 to C8divalent saturated aliphatic hydrocarbon group. L^(X8) is preferably asingle bond or a C1 to C8 divalent saturated aliphatic hydrocarbongroup, and more preferably a single bond or a methylene group. L^(X9) ispreferably a single bond or a C1 to C8 divalent saturated aliphatichydrocarbon group, and more preferably a single bond or a methylenegroup. W^(X1) is preferably a C3 to C10 divalent saturated alicyclichydrocarbon group, and more preferably a cyclohexanediyl group or anadamantanediyl group.

Examples of the group represented by L⁵⁵ include the following ones.

L⁵⁵ is preferably a single bond, methylene group, ethylene group or thegroups represented by formula (L1-1), and more preferably a single bondor the groups represented by formula (L1-1).

Examples of the structural unit (a5-1) include the following ones.

Examples of the structural unit (a5) include the structural units of theformulae (a5-1-1) to (a5-1-18) in which a methyl group corresponding toR⁵¹ has been replaced by a hydrogen atom.

When Resin (A) has the structural unit (a5), the proportion thereof ispreferably 1 to 30% by mole, more preferably 2 to 20% by mole, and stillmore preferably 3 to 15% by mole, with respect to the total structuralunits (100% by mole) of Resin (A).

Resin (A) is preferably a resin which consists of the structural unit(I) and another structural unit (a1) and a resin which consists of thestructural unit (I), another structural unit (a1) and the structuralunit (s), more preferably a resin which consists of the structural unit(I), another structural unit (a1) and the structural unit (s).

In Resin (A), the structural unit (a1) other than the structural unit(I) is preferably at least one of the structural unit (a1-1) and thestructural unit (a1-2) (preferably the structural unit having acyclohexyl group or a cyclopentyl group), and more preferably is thestructural unit (a1-2).

The structural unit (s) is preferably at least one of the structuralunit (a2) and the structural unit (a3). The structural unit (a2) ispreferably the structural unit represented by formula (a2-1). Thestructural unit (a3) is preferably the structural unit (a3-4).

The structural unit (t) is preferably the structural unit (a4) such as astructural unit which has a fluorine atom.

Resin (A) can be produced by a known polymerization method, for example,radical polymerization method, using one or more kinds of monomers asdescribed above. The proportions of the structural units in Resin (A)can be adjusted by changing the amount of a monomer used inpolymerization.

The weight average molecular weight of Resin (A) is preferably 2,000 ormore (more preferably 2,500 or more, and still more preferably 3,000 ormore), and 50,000 or less (more preferably 30,000 or less, and stillmore preferably 15,000 or less).

The weight average molecular weight is a value determined by gelpermeation chromatography using polystyrene as the standard product. Thedetailed condition of this analysis is described in Examples.

<Resin (X)>

Examples of Resin (X) include one having the structural unit (t),preferably a resin which has the structural unit (a4) and no structuralunit (a1), and preferably a resin which has the structural unit (a4)having a fluorine atom.

When the Resin (X) has the structural unit (a4), the proportion thereofis preferably 40% by mole or more, more preferably 45% by mole or more,and still more preferably 50% by mole or more, with respect to the totalstructural units (100% by mole) of the Resin (X).

Resin (X) can further have the structural unit (a2), the structural unit(a3), the structural unit (a5) and/or the well-known structural unit inthe art. Resin (X) preferably consists of the structural units (t), morepreferably comprises the structural units (a4) and the structural units(a5) as the structural units (t), still more preferably comprises thestructural units (a4) having a fluorine atom as the structural units(t).

Resin (X) can be produced by a known polymerization method, for example,radical polymerization method, using one or more kinds of monomers asdescribed above. The proportions of the structural units in the Resin(X) can be adjusted by changing the amount of a monomer used inpolymerization.

The weight average molecular weight of Resin (X) is preferably 5,000 ormore (more preferably 6,000 or more), and 80,000 or less (morepreferably 60,000 or less).

When the photoresist composition further contains Resin (X), theproportion thereof is preferably 1 to 60 parts by mass, more preferably1 to 50 parts by mass, and still more preferably 1 to 40 parts by mass,further more preferably 2 to 30 parts by mass, still further morepreferably 2 to 8 parts by mass, with respect to 100 parts by mass ofResin (A).

The photoresist composition preferably further contains Resin (X) whichhas a structural unit having a fluorine atom and no acid-labile group.The total proportion of Resin (A) and the Resin (X) is preferably 80% bymass to 99% by mass, more preferably 90% by mass to 99% by mass, withrespect to the total amount of solid components of the photoresistcomposition.

The proportion of the solid components in the photoresist compositionand that of the resins in the solid components can be measured with aknown analytical method such as liquid chromatography and gaschromatography.

<Acid Generator (B)>

The acid generator is a compound which can be decomposed by radiationincluding light to generate an acid. The acid acts catalytically toResin (A), resulting in removing a leaving group from the resin.

The acid generator (B) can be an ionic acid generator or a non-ionicacid generator. The acid generator (B) may be used any an ionic acidgenerator and a non-ionic acid generator. Examples of the nonioniccompounds for the acid generator include organic halogenated compounds;sulfonate esters, e.g. 2-nitrobenzylester, aromatic sulfonates,oximesulfonate, N-sulfonyloxyimide, sulfonyloxyketone, anddiazonaphtoquione 4-sulfonate; sulfones, e.g., disulfone, ketosulfone,and sulfonium diazomethane. The ionic compounds for the acid generatorinclude onium salts having an onium cation, e.g., diazonium salts,phosphonium salts, sulfonium salts and iodonium salts. Examples of theanions of onium salt include a sulfonic acid anion, a sulfonylimideanion, sulfonylmethide anion.

As the acid generator, the compounds giving an acid by radiation can beused, which are mentioned in JP63-26653A1, JP55-164824A1, JP62-69263A1,JP63-146038A1, JP63-163452A1, JP62-153853A1, JP63-146029A1, U.S. Pat.No. 3,779,778B1, U.S. Pat. No. 3,849,137B1, DE3914407 and EP126,712A1.The acid generator for the photoresist composition can be produced bythe method described in the above-mentioned documents.

The acid generator is preferably a fluorine-containing compound, morepreferably a salt represented by formula (B1) (which is sometimesreferred to as “acid generator (B1)”):

wherein Q and Q² each respectively represent a fluorine atom or a C1 toC6 perfluoroalkyl group,

L^(b1) represents a C1 to C24 divalent saturated hydrocarbon group wherea methylene group can be replaced by an oxygen atom or a carbonyl groupand a hydrogen atom can be replaced by a hydroxyl group or fluorineatom, and Y represents an optionally substituted methyl group or anoptionally substituted C3 to C18 alicyclic hydrocarbon group where amethylene group can be replaced by an oxygen atom, a carbonyl group or asulfonyl group, and Z⁺ represents an organic cation.

Examples of the perfluoroalkyl group of Q¹ and Q² includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl and perfluorohexyl groups.

Q¹ and Q² independently are preferably trifluoromethyl or fluorine atom,and both of Q¹ and Q² are more preferably a fluorine atom.

Examples of the divalent saturated hydrocarbon group of L^(b1) includeany of a chain or a branched alkanediyl group, a divalent mono- or apoly-alicyclic saturated hydrocarbon group, and a combination thereof.

Specific examples of the chain alkanediyl group include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl,dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl,pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diylgroups.

Specific examples of the branched chain alkanediyl group includeethane-1,1-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-2,2-diyl,pentane-1,4-diyl, pentane-2,4-diyl, 2-methylpropane-1,3-diyl,2-methylpropane-1,2-diyl and 2-methylbutane-1,4-diyl groups.

Specific examples of the mono-alicyclic saturated hydrocarbon groupinclude a cycloalkanediyl group such as cyclobutan-1,3-diyl,cyclopentan-1,3-diyl, cyclohexane-1,4-diyl and cyclooctan-1,5-diylgroups.

Specific examples of the poly-alicyclic saturated hydrocarbon groupinclude norbornane-1,4-diyl, norbornane-2,5-diyl, adamantane-1,5-diyland adamantane-2,6-diyl groups.

Examples of the saturated hydrocarbon group of L^(b1) in which amethylene group has been replaced by oxygen atom or a carbonyl groupinclude the following groups represented by formula (b1-1) to formula(b1-3):

wherein L^(b2) represents a single bond or a C1 to C22 divalentsaturated hydrocarbon group where a hydrogen atom can be replaced by afluorine atom; L^(b3) represents a single bond or a C1 to C22 divalentsaturated hydrocarbon group where a hydrogen atom can be replaced by afluorine atom or a hydroxy group, and a methylene group can be replacedby an oxygen atom or a carbonyl group; provided that the total number ofthe carbon atoms contained in the group of L^(b2) and L^(b3) is 22 orless;

L^(b4) represents a single bond or a C1 to C22 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom;

L^(b5) represents a single bond or a C1 to C22 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom or a hydroxy group, and a methylene group can be replaced by anoxygen atom or a carbonyl group; provided that the total number of thecarbon atoms contained in the group of L^(b4) and L^(b5) is 22 or less;

L^(b6) represents a single bond or a C1 to C23 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom or a hydroxy group; L^(b7) represents a single bond or a C1 to C23divalent saturated hydrocarbon group where a hydrogen atom can bereplaced by a fluorine atom or a hydroxy group, and a methylene groupcan be replaced by an oxygen atom or a carbonyl group; provided that thetotal number of the carbon atoms contained in the group of L^(b6) andL^(b7) is 23 or less, and * represents a binding position to —Y.

In formula (b1-1) to formula (b1-3), when a methylene group has beenreplaced by an oxygen atom or a carbonyl group, the carbon number of thesaturated hydrocarbon group corresponds to the number of the carbon atombefore replacement.

Examples of the divalent saturated hydrocarbon group are the sameexamples as the divalent saturated hydrocarbon group of L^(b1).

L^(b2) is preferably a single bond.

L^(b3) is preferably a C1 to C4 divalent saturated hydrocarbon group.

L^(b4) is preferably a C1 to C8 divalent saturated hydrocarbon groupwhere a hydrogen atom can be replaced by a fluorine atom.

L^(b5) is preferably a single bond or a C1 to C8 divalent saturatedhydrocarbon group.

L^(b6) is preferably a single bond or a C1 to C4 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom.

L^(b7) is preferably a single bond or a C1 to C18 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom or a hydroxy group, and where a methylene group can be replaced byan oxygen atom or a carbonyl group.

Among these, the group represented by the formula (b1-1) or the formula(b1-3) is preferred.

Examples of the divalent group represented by the formula (b1-1) includethe following groups represented by formula (b1-4) to formula (b1-8):

wherein L^(b8) represents a single bond or a C1 to C22 divalentsaturated hydrocarbon group where a hydrogen atom can be replaced by afluorine atom or a hydroxy group;

L^(b9) represents a C1 to C20 divalent saturated hydrocarbon group;

L¹⁰ represents a single bond or a C1 to C19 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom or a hydroxy group; provided that the total number of the carbonatoms contained in the group of L^(b9) and L^(b10) is 20 or less;

L^(b11) represents a C1 to C₂₁ divalent saturated hydrocarbon group;

L^(b12) represents a single bond or a C1 to C20 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom or a hydroxy group; provided that the total number of the carbonatoms contained in the group of L^(b11) and L^(b12) is 21 or less;

L^(b13) represents a C1 to C19 divalent saturated hydrocarbon group;

L^(b14) represents a single bond or a C1 to C18 divalent saturatedhydrocarbon group; L^(b15) represents a single bond or a C1 to C18divalent saturated hydrocarbon group where a hydrogen atom can bereplaced by a fluorine atom or a hydroxy group; provided that the totalnumber of the carbon atoms contained in the group of L^(b13), L^(b14)and L^(b15) is 19 or less; L^(b16) represents a C1 to C18 divalentsaturated hydrocarbon group; L^(b17) represents a C1 to C18 divalentsaturated hydrocarbon group; L^(b18) represents a single bond or a C1 toC17 divalent saturated hydrocarbon group where a hydrogen atom can bereplaced by a fluorine atom or a hydroxy group; provided that the totalnumber of the carbon atoms contained in the group of L^(b16), L^(b17)and L^(b18) is 19 or less, and

* represents a binding position to —Y.

L^(b8) is preferably a C1 to C4 divalent saturated hydrocarbon group.

L^(b9) is preferably a C1 to C8 divalent saturated hydrocarbon group.

L^(b10) is preferably a single bond or a C1 to C19 divalent saturatedhydrocarbon group, and more preferably a single bond or a C1 to C8divalent saturated hydrocarbon group.

L^(b11) is preferably a C1 to C8 divalent saturated hydrocarbon group.

L^(b12) is preferably a single bond or a C1 to C8 divalent saturatedhydrocarbon group.

L^(b13) is preferably a C1 to C12 divalent saturated hydrocarbon group.

L^(b14) is preferably a single bond or a C1 to C6 divalent saturatedhydrocarbon group.

L^(b15) is preferably a single bond or a C1 to C18 divalent saturatedhydrocarbon group, and more preferably a single bond or a C1 to C8divalent saturated hydrocarbon group.

L^(b16) is preferably a C1 to C12 divalent saturated hydrocarbon group.

L^(b17) is preferably a C1 to C6 divalent saturated hydrocarbon group.

L^(b18) is preferably a single bond or a C1 to C17 divalent saturatedhydrocarbon group, and more preferably a single bond or a C1 to C4divalent saturated hydrocarbon group.

Examples of the divalent group represented by the formula (b1-3) includethe following groups represented by formula (b1-9) to formula (b1-11):

wherein L^(b19) represents a single bond or a C1 to C23 divalentsaturated hydrocarbon group where a hydrogen atom can be replaced by afluorine atom;

L^(b20) represent a single bond or a C1 to C23 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group can be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group can bereplaced by a hydroxy group, provided that the total number of thecarbon atoms contained in the group of L^(b19) and L^(b20) is 23 orless;

L²¹ represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom;

L^(b22) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b23) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group can be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group can bereplaced by a hydroxy group, provided that the total number of thecarbon atoms contained in the group of L^(b21), L^(b22) and L^(b23) is21 or less;

L^(b24) represents a single bond or a C1 to C20 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom;

L^(b25) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b26) represents a single bond or a C1 to C20 divalent saturatedhydrocarbon group where a hydrogen atom can be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group can be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group can bereplaced by a hydroxy group, provided that the total number of thecarbon atoms contained in the group of L^(b24), L^(b25) and L^(b26) is21 or less; and * represents a binding position to —Y.

In formula (b1-9) to formula (b1-11), when a hydrogen atom has beenreplaced by an acyloxy group, the carbon number of the saturatedhydrocarbon group corresponds to the number of the carbon atom, CO and Oin addition to the carbon number of the saturated hydrocarbon group.

For formula (b1-9) to formula (b1-11), examples of the divalentsaturated hydrocarbon group include an alkanediyl and a monocyclic orpolycyclic divalent saturated hydrocarbon group, and a combination oftwo or more such groups.

Examples of the acyloxy group include acetyloxy, propionyloxy,butyryloxy, cyclohexylcarbonyloxy and adamantylcarbonyloxy groups.

Examples of the acyloxy group having a substituent includeoxoadamantylcarbonyloxy, hydroxyadamantylcarbonyloxy,oxocyclohexylcarbonyloxy and hydroxycyclohexylcarbonyloxy groups.

Examples of the group represented by the formula (b1-4) include thefollowing ones.

Examples of the group represented by the formula (b1-5) include thefollowing ones.

Examples of the group represented by the formula (b1-6) include thefollowing ones.

Examples of the group represented by the formula (b1-7) include thefollowing ones.

Examples of the group represented by the formula (b1-8) include thefollowing ones.

Examples of the group represented by the formula (b1-2) include thefollowing ones.

Examples of the group represented by the formula (b1-9) include thefollowing ones.

Examples of the group represented by the formula (b1-10) include thefollowing ones.

Examples of the group represented by the formula (b1-11) include thefollowing ones.

Examples of the monovalent alicyclic hydrocarbon group of Y includegroups represented by formula (Y1) to formula (Y11) and formula (Y36) toformula (Y38). Examples of the monovalent alicyclic hydrocarbon group ofYin which a methylene group has been replaced by an oxygen atom, acarbonyl group or a sulfonyl group include groups represented by formula(Y12) to formula (Y35).

The ketal ring may have two oxygen atoms each bonded to a carbon atomdifferent to one another. In the ketal ring, a methylene group bonded tothe oxygen atom preferably has no fluorine atom.

Among these, the alicyclic hydrocarbon group is preferably any one ofgroups represented by the formula (Y1) to the formula (Y20), the formula(Y30), and the formula (Y31), more preferably any one of groupsrepresented by the formula (Y11), (Y15), (Y20), (Y30) and (Y31), andstill more preferably group represented by the formula (Y11), (Y15) or(Y30).

Examples of the substituent for the methyl group of Y include a halogenatom, a hydroxyl group, a C3 to C16 alicyclic hydrocarbon group, a C6 toC18 aromatic hydrocarbon group, a glycidyloxy group and—(CH₂)_(j2)—O—CO—R^(b1)— in which R^(b1) represents an C1 to C16 alkylgroup, a C3 to C16 alicyclic hydrocarbon group, or a C6 to C18 aromatichydrocarbon group, and j2 represents an integer of 0 to 4.

Examples of the substituent for the alicyclic group of Y include ahalogen atom, a hydroxyl group, a C1 to C12 alkyl group, a hydroxygroup-containing C1 to C12 alkyl group, a C3 to C16 alicyclichydrocarbon group, a C1 to C12 alkoxy group, a C6 to C18 aromatichydrocarbon group, a C7 to C21 aralkyl group, a C2 to C4 acyl group, aglycidyloxy group and —(CH₂)_(j2)—O—CO—R^(b1)— in which R^(b1)represents an C1 to C16 alkyl group, a C3 to C16 alicyclic hydrocarbongroup, or a C6 to C18 aromatic hydrocarbon group, and j2 represents aninteger of 0 to 4.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alicyclic hydrocarbon group include a cyclopentyl group,a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexylgroup, a cycloheptyl group, a cyclooctyl group, an adamantyl group andnorbornyl group.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl,decyl, undecyl and dodecyl groups.

Examples of the hydroxy group-containing alkyl group includehydroxymethyl and hydroxyethyl groups.

Examples of the alkoxyl group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxygroups.

Examples of the aralkyl group include benzyl, phenethyl, phenylpropyl,naphthylmethyl and naphthylethyl groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of Y include the groups below. * represents a binding positionto L^(b1).

When Y is a methyl group and L^(b1) is a C1 to C17 divalent chain orbranched saturated hydrocarbon group, a —CH₂— which is bonded to Y ispreferably replaced by an oxygen atom or a carbonyl group.

Y is preferably a C3 to C18 alicyclic hydrocarbon group which can have asubstituent, more preferably an adamantyl group which may have asubstituent and in which a methylene group can be replaced by an oxygenatom, a carbonyl group or a sulfonyl group, and still more preferably anadamantyl group, a hydroxyadamantyl group, an oxoadamantyl group or agroup below.

The sulfonic acid anion for the salt represented by formula (B1) ispreferably anions represented by formula (B1-A-1) to formula (B1-A-54),and more preferably anions represented by formula (B1-A-1) to formula(B1-A-4), formula (B1-A-9), formula (B1-A-10), formulae (B1-A-24) to(B1-A-33), formulae (B1-A-36) to (B1-A-40), and formulae (B1-A-47) to(B1-A-54).

In formula (B1-A-1) to formula (B1-A-54), R^(i2) to R^(i7) independentlyrepresent a C1 to C4 alkyl group, and preferably a methyl group or anethyl group. R^(i8) represent a C1 to C12 aliphatic hydrocarbon group,preferably a C1 to C4 alkyl group, a C5 to C12 monovalent alicyclichydrocarbon group or a group formed by a combination thereof, morepreferably a methyl group, an ethyl group, a cyclohexyl group or anadamantyl group. L⁴ represents a single bond or a C1 to C4 alkanediylgroup. Q¹ and Q² represent the same meaning as defined above.

Specific examples of the sulfonic acid anion in the salt represented byformula (B1) include anions mentioned in JP2010-204646A1.

Among them, preferred examples of the sulfonic acid anion for the saltrepresented by formula (B1) include anions represented by formulae(B1a-1) to (B1a-30).

Among them, preferred examples of the sulfonic acid anion include anionsrepresented by formulae (B1a-1) to (B1a-3), (B1a-7) to (B1a-16),(B1a-18), (B1a-19) and (B1a-22) to (B1a-30).

Examples of the organic cation represented by Z⁺ include an organiconium cation such as an organic sulfonium cation, an organic iodoniumcation, an organic ammonium cation, a benzothiazolium cation and anorganic phosphonium cation, and an organic sulfonium cation and anorganic iodonium cation are preferred, and an arylsulfonium cation ismore preferred. Z⁺ of the formula (B1) is preferably represented by anyof the formula (b2-1) to the formula (b2-4):

wherein R^(b4), R^(b5) and R^(b6) independently represent a C1 to C30aliphatic hydrocarbon group, a C3 to C36 alicyclic hydrocarbon group ora C6 to C36 aromatic hydrocarbon group, a hydrogen atom contained in analiphatic hydrocarbon group can be replaced by a hydroxy group, a C1 toC12 alkoxy group, a C3 to C12 alicyclic hydrocarbon group or a C6 to C18aromatic hydrocarbon group, a hydrogen atom contained in an alicyclichydrocarbon group can be replaced by a halogen atom, a C1 to C18aliphatic hydrocarbon group, a C2 to C4 acyl group or a glycidyloxygroup, a hydrogen atom contained in an aromatic hydrocarbon group can bereplaced by a halogen atom, a hydroxy group or a C1 to C12 alkoxy group,or R^(b4) and R^(b5) can be bonded together with a sulfur atom bondedthereto to form a sulfur-containing ring, a methylene group contained inthe ring can be replaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b7) and R^(b8) in each occurrence independently represent a hydroxygroup, a C1 to C12 aliphatic hydrocarbon group or a C1 to C12 alkoxygroup, m2 and n2 independently represent an integer of 0 to 5;

R^(b9) and R^(b10) each independently represent a C1 to C36 aliphatichydrocarbon group or a C3 to C36 alicyclic hydrocarbon group, or R^(b9)and R^(b10) can be bonded together with a sulfur atom bonded thereto toform a sulfur-containing ring, and a methylene group contained in thering can be replaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b11) represents a hydrogen atom, a C1 to C36 aliphatic hydrocarbongroup, a C3 to C36 alicyclic hydrocarbon group or a C6 to C18 aromatichydrocarbon group;

R^(b12) represents a C1 to C12 aliphatic hydrocarbon group, a C3 to C18alicyclic hydrocarbon group and a C6 to C18 aromatic hydrocarbon group,a hydrogen atom contained in an aliphatic hydrocarbon group can bereplaced by a C6 to C18 aromatic hydrocarbon group, and a hydrogen atomcontained in an aromatic hydrocarbon group can be replaced by a C1 toC12 alkoxy group or a C1 to C12 alkyl carbonyloxy group;

R^(b1) and R^(b12) can be bonded together with —CH—CO— bonded thereto toform a ring, and a methylene group contained in the ring can be replacedby an oxygen atom, a —SO— or a carbonyl group;

R^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) in eachoccurrence independently represent a hydroxy group, a C1 to C12aliphatic hydrocarbon group or a C1 to C12 alkoxy group;

L^(b31) represents —S— or —O—;

o2, p2, s2 and t2 independently represent an integer of 0 to 5;

q2 or r2 independently represent an integer of 0 to 4; and

u2 represents an integer of 0 or 1.

Examples of the aliphatic group preferably include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-octyl and 2-ethylhexyl groups. Among these, the aliphatic hydrocarbongroup of R^(b9) to R^(b12) is preferably a C1 to C12 aliphatichydrocarbon group.

Examples of the alicyclic hydrocarbon group preferably includemonocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecylgroups; and polycyclic groups such as decahydronaphtyl, adamantyl andnorbornyl groups as well as the following groups. * represents a bindingposition.

Among these, the alicyclic hydrocarbon group of R^(b9) to R^(b12) ispreferably a C3 to C18 alicyclic hydrocarbon group, and more preferablya C4 to C12 alicyclic hydrocarbon group.

Examples of the alicyclic hydrocarbon group where a hydrogen atom can bereplaced by an aliphatic hydrocarbon group include methylcyclohexyl,dimethylcyclohexyl, 2-alkyladamantane-2-yl, methylnorbornyl andisobornyl groups. In the alicyclic hydrocarbon group where a hydrogenatom can be replaced by an aliphatic hydrocarbon group, the total numberof the carbon atoms of the alicyclic hydrocarbon group and the aliphatichydrocarbon group is preferably 20 or less.

Examples of the aromatic hydrocarbon group preferably include an arylgroup such as phenyl, tolyl, xylyl, cumenyl, mesityl, p-ethylphenyl,p-tert-butylphenyl, p-cyclohexylphenyl, p-adamantylphenyl, biphenyl,naphthyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

When the aromatic hydrocarbon includes an aliphatic hydrocarbon group oran alicyclic hydrocarbon group, a C1 to C18 aliphatic hydrocarbon groupor a C3 to C18 alicyclic hydrocarbon group is preferred.

Examples of the aromatic hydrocarbon group where a hydrogen atom can bereplaced by an alkoxy group include a p-methoxyphenyl group.

Examples of the aliphatic hydrocarbon group where a hydrogen atom can bereplaced by an aromatic hydrocarbon group include an aralkyl group suchas benzyl, phenethyl phenylpropyl, trityl, naphthylmethyl andnaphthylethyl groups.

Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, and dodecyloxy groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkylcarbonyloxy group include methylcarbonyloxy,ethylcarbonyloxy, n-propylcarbonyloxy, isopropylcarbonyloxy,n-butylcarbonyloxy, sec-butylcarbonyloxy, tert-butyl carbonyloxy,pentylcarbonyloxy, hexylcarbonyloxy, octylcarbonyloxy and2-ethylhexylcarobonyloxy groups.

The sulfur atom-containing ring which is formed by R^(b4) and R^(b5) canbe a monocyclic or polycyclic group, which may be an aromatic ornon-aromatic group, and which may be a saturated or unsaturated group.The ring is preferably a ring having 3 to 18 carbon atoms, and morepreferably a ring having 4 to 13 carbon atoms. Examples of the sulfuratom-containing ring include a 3- to 12-membered ring, preferably a 3-to 7-membered ring, examples thereof include the following rings.

Examples of the ring formed by R^(b9) and R^(b10) include any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring.

Examples of the ring include thiolane-1-ium ring (tetrahydrothiopheniumring), thian-1-ium ring and 1,4-oxathian-4-ium ring.

Examples of the ring formed by R^(b11) and R^(b12) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring.

Examples of the ring include oxocycloheptane ring, oxocyclohexane ring,oxonorbornane ring and oxoadamantane ring.

Among the cations represented by formula (b2-1) to formula (b2-4), thecation represented by formula (b2-1) is preferred.

Examples of the cation represented by formula (b2-1) include thefollowing ones.

Examples of the cation represented by formula (b2-2) include thefollowing ones.

Examples of the cation represented by formula (b2-3) include thefollowing ones.

Examples of the cation represented by formula (b2-4) include thefollowing ones.

The acid generator (B) is generally a compound which consists of theabove sulfonate anion with an organic cation. The above sulfonic acidanion and the organic cation may optionally be combined. Preferredcombination is a combination of any of the anion represented by theformula (B1a-1) to the formula (B1a-3), the formula (B1a-7) to theformula (B1a-16), the formula (B1a-18), the formula (B1a-19) and theformula (B1a-22) to the formula (B1a-30) with the cation represented bythe formula (b2-1) or the formula (b2-3).

Examples of preferred acid generators (B1) include those represented byformulae (B1-1) to (B1-48). Among them, the acid generators (B1)represented by formulae (B1-1), (B1-3), (B1-5), (B1-7), (B1-11),(B1-14), (B1-20), (B1-21), (B1-23), (B1-26), (B1-29), (B1-31) and(B1-40) to (B1-48), which contain an arylsulfonium cation, arepreferred.

In the photoresist composition of the disclosure, the proportion of theacid generator (B) is preferably 1 parts by mass or more and morepreferably 3 parts by mass or more, and preferably 30 parts by mass orless and more preferably 25 parts by mass or less with respect to 100parts by mass of Resin (A).

In the photoresist composition of the disclosure, the acid generator (B)can be used as one kind of the salt or as two or more kinds of them.

<Solvent (E)>

The proportion of a solvent (E) is 90% by mass or more, preferably 92%by mass or more, and more preferably 94% by mass or more, and alsopreferably 99% by mass or less and more preferably 99.9% by mass or lessof the total amount of the photoresist composition. The proportion ofthe solvent (E) can be measured with a known analytical method such as,for example, liquid chromatography and gas chromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate andpropyleneglycolmonomethylether acetate; glycol ethers such aspropyleneglycolmonomethylether; esters such as ethyl lactate, butylacetate, amyl acetate and ethyl pyruvate; ketones such as acetone,methyl isobutyl ketone, 2-heptanone and cyclohexanone; and cyclic esterssuch as γ-butyrolactone. These solvents may be used as a single solventor as a mixture of two or more solvents.

<Quencher>

The photoresist composition of the present disclosure can furthercontain a quencher such as a basic nitrogen-containing organic compoundor a salt which generates an acid lower in acidity than an acidgenerated from the acid generators and which is sometimes referred to as“weak acid salt”.

Examples of the basic nitrogen-containing organic compound include anamine and ammonium salts. The amine can be an aliphatic amine or anaromatic amine. The aliphatic amine includes any of a primary amine,secondary amine and tertiary amine.

Specific examples of the amine include 1-naphtylamine, 2-naphtylamine,aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine,didecylamine, triethylamine, trimethylamine, tripropylamine,tributylamine, tripentylamine, trihexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, methyldibutylamine,methyldipentylamine, methyldihexylamine, methyldicyclohexylamine,methyldiheptylamine, methyldioctylamine, methyldinonylamine,methyldidecylamine, ethyldibutylamine, ethyldipentylamine,ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine,ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine,tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylene diamine, hexamethylene diamine,4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl) ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy) ethane, di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine and bipyridine. Among them,diisopropylaniline is preferred, particularly 2,6-diisopropylaniline ismore preferred.

Specific examples of the ammonium salt include tetramethylammoniumhydroxide, tetraisopropylammonium hydroxide, tetrabutylammoniumhydroxide, tetrahexylammnonium hydroxide, tetraoctylamnonium hydroxide,phenyltrimethyl ammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate and choline.

As to a weak acid salt, the “acidity” for a weak acid salt can berepresented by acid dissociation constant, pKa, of an acid generatedfrom the weak acid salt. Examples of the weak acid salt include a saltgenerating an acid of pKa represents generally more than −3, preferably−1 to 7, and more preferably 0 to 5.

Specific examples of the weak acid salt include the following salts, theweak acid inner salt of formula (D), and salts as disclosed inJP2012-229206A1, JP2012-6908A1, JP2012-72109A1, JP2011-39502A1 andJP2011-191745A1, preferably the salt of formula (D).

wherein R^(D1) and R^(D2) in each occurrence independently represent aC1 to C12 hydrocarbon group, a C1 to C6 alkoxy group, a C2 to C7 acylgroup, a C2 to C7 acyloxy group, a C2 to C7 alkoxycarbonyl group, anitro group or a halogen atom, and m′ and n′ independently represent aninteger of 0 to 4.

The hydrocarbon group for R^(D1) and R^(D2) includes any of an aliphatichydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group and a combination thereof.

Examples of the aliphatic hydrocarbon group include an alkyl group suchas methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl,pentyl, hexyl and nonyl groups.

The alicyclic hydrocarbon group is any one of monocyclic or polycyclichydrocarbon group, and saturated or unsaturated hydrocarbon group.

Examples thereof include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl and cyclododecyl groups;adamantyl and norbornyl groups. The alicyclic hydrocarbon group ispreferably saturated hydrocarbon group.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, 1-naphthyl, 2-naphthyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl,4-butylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl,anthryl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the combination thereof include an alkyl-cycloalkyl group, acycloalkyl-alkyl group, an aralkyl group such as phenylmethyl,1-phenylethyl, 2-phenylethyl, 1-phenyl-1-propyl, 1-phenyl-2-propyl,2-phenyl-2-propyl, 3-phenyl-1-propyl, 4-phenyl-1-butyl,5-phenyl-1-pentyl and 6-phenyl-1-hexyl groups.

Examples of the alkoxy group include methoxy and ethoxy groups.

Examples of the acyl group include acetyl, propanonyl, benzoyl andcyclohexanecarbonyl groups.

Examples of the acyloxy group include a group in which oxy group (—O—)bonds to an acyl group.

Examples of the alkoxycarbonyl group include a group in which thecarbonyl group (—CO—) bonds to the alkoxy group.

Examples of the halogen atom include a chlorine atom, a fluorine atomand bromine atom.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlypreferably represent a C1 to C8 alkyl group, a C3 to C10 cycloalkylgroup, a C1 to C6 alkoxy group, a C2 to C4 acyl group, a C2 to C4acyloxy group, a C2 to C4 alkoxycarbonyl group, a nitro group or ahalogen atom.

m′ and n′ independently preferably represent an integer of 0 to 3, morepreferably an integer of 0 to 2, and more preferably 0.

The proportion of the quencher is preferably 0.01% by mass to 5% bymass, more preferably 0.01% by mass to 4% by mass, still more preferably0.01% by mass to 3% by mass, with respect to the total amount of solidcomponents of the photoresist composition.

<Other Ingredients>

The photoresist composition can also include another ingredient (whichis sometimes referred to as “other ingredient (F)”). The otheringredient (F) includes various additives such as sensitizers,dissolution inhibitors, surfactants, stabilizers, and dyes, as needed.

<Preparing the Photoresist Composition>

The photoresist composition of the disclosure can be prepared by mixinga resin (A) and an acid generator (B) as well as Resin (X), a quenchersuch as a weak acid inner salt (D), a solvent (E) and another ingredient(F), as needed. There is no particular limitation on the order ofmixing. The mixing can be performed in an arbitrary order. Thetemperature of mixing may be adjusted to an appropriate temperature inthe range of 10 to 40° C., depending on the kinds of the resin andsolubility in the solvent (E) of the resin. The time of mixing may beadjusted to an appropriate time in the range of 0.5 to 24 hours,depending on the mixing temperature. There is no particular limitationto the tool for mixing. An agitation mixing may be adopted.

After mixing the above ingredients, the present photoresist compositionscan be prepared by filtering the mixture through a filter having about0.003 to 0.2 μm of its pore diameter.

<Method for Producing a Photoresist Pattern>

The method for producing a photoresist pattern of the present disclosureincludes the steps of:

(1) applying a photoresist composition of the present disclosure onto asubstrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer with butyl acetate.

Applying the photoresist composition onto a substrate can generally becarried out through use of a photoresist application device, such as aspin coater known in the field of semiconductor microfabricationtechnique.

Examples of the substrate include inorganic substrates such as silicon,SiN, SiO₂ or SiN, and Spin-on glass [SOG] or other coated inorganicsubstrates. Substrate which can be used include washed one, and one onwhich an organic antireflection film formed before application of thephotoresist composition.

A commercially available antireflection composition can be used for theorganic antireflection film.

The solvent evaporates from the photoresist composition to form acomposition layer. Drying the composition on a substrate can be carriedout using a heating device such as a hotplate (so-called “prebake”), adecompression device, or a combination thereof. The temperature ispreferably in the range of 50 to 200° C. The time for heating ispreferably 10 to 180 seconds, more preferably 30 to 120 seconds. Thepressure is preferably in the range of 1 to 1.0×10⁵ Pa.

The thickness of the composition layer is usually 20 to 1000 nm,preferably 50 to 400 nm. The thickness can be adjusted by changingconditions for a photoresist application device.

The composition layer thus obtained is generally exposed using anexposure apparatus or a liquid immersion exposure apparatus. Theexposure is generally carried out using with various types of exposurelight source, such as irradiation with ultraviolet lasers, i.e., KrFexcimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193nm), F₂ excimer laser (wavelength: 157 nm), irradiation with harmoniclaser light of far-ultraviolet or vacuum ultra violetwavelength-converted laser light from a solid-state laser source (YAG orsemiconductor laser or the like), or irradiation with electron beam, EUVor the like. The composition layer is preferably exposed using a liquidimmersion exposure apparatus with ArF excimer laser. In thespecification, such exposure to radiation is sometimes referred to becollectively called as exposure. The exposure is generally carried outin the manner of immersion exposure, e.g., in such a way that liquidmedium is placed in contact with a composition layer. When immersionexposure is conducted, the surface of composition layer can optionallybe washed with an aqueous chemical before and/or after the exposure.

The liquid immersion medium for liquid immersion exposure is preferablya liquid which can maintain transparent for exposing with ArF excimerlaser and whose temperature coefficient of the refractive index is so assmall to minimize the distortion of the optics image reflected on thecomposition layer. Preferred examples of such liquid immersion mediuminclude water, specifically ultrapure water, owing to its availability.

When water is used for the liquid immersion medium, a small amount of anadditive capable of decreasing surface tension of the water andincreasing surface activity of the water can be added to the water.

As such additive, preferred is an additive which does not dissolve acomposition layer and which has substantially no effect on optics coatat the undersurface of a lens element which the exposure apparatus has.

The exposure amount or quantity can be controlled depending on thephotoresist composition to be used, the photoresist pattern to beproduced or the exposure source for the production. The exposure amountor quantity is preferably 5 to 50 mJ/cm².

Exposure can be conducted twice or more times. If exposure is conductedtwice or more times, each step can be conducted using the same procedureand exposure source as those of another time or a different procedureand exposure source from those of another time.

After exposure, the composition layer is subjected to a heat treatment(so-called “post-exposure bake”). The heat treatment can be carried outusing a heating device such as a hotplate. The heating temperature isgenerally in the range of 50 to 200° C., preferably in the range of 70to 150° C. Temperature for heating is generally 5 to 60° C. The time fordeveloping is preferably 10 to 180 seconds, more preferably 30 to 120seconds.

The developing of the baked composition film is usually carried out witha developer using a development apparatus.

The development for obtaining a photoresist pattern is usually carriedout with a developer containing butyl acetate. The developer can furtherinclude a solvent other than butyl acetate.

The solvent other than butyl acetate can be any one of various organicsolvents used in the art, examples of which include ketone solvents suchas 2-hexanone, 2-heptanone; glycol ether ester solvents such aspropyleneglycolmonomethylether acetate; ester solvents; glycol ethersolvents such as the propyleneglycolmonomethylether; amide solvents suchas N,N-dimethylacetamide; aromatic hydrocarbon solvents such as anisole.

In the developer containing butyl acetate, the amount of butyl acetateis preferably 50% by mass to 100% by mass of the developer. Thedeveloper still more preferably consists essentially of butyl acetate.

Developers containing an organic solvent can contain a surfactant.

The surfactant is not limited to a specific one, and examples of thatinclude an ionic surfactant or a nonionic surfactant, specifically afluorine-based surfactant and a silicon-based surfactant.

Developing can be conducted in the manner of dipping method, paddlemethod, spray method and dynamic dispensing method.

Examples of developing procedure include

dipping method in which a post-exposure baked composition layer togetherwith the substrate having the layer is immersed in a developing solutionwith which a vessel is filled for a certain period of time;

paddle method in which developing is conducted through heaping up andkeeping a developer on a post-exposure baked composition layer bysurface tension for a certain period of time;

spray method in which developing is conducted by spraying a developer toa post-exposure baked composition layer on its surface tension; and

dynamic dispensing method in which dispensing a developer is conductedwhile adjusting a dispensing nozzle to a certain speed and rotating thesubstrate on which a post-exposure baked composition layer forms.

For the process of the present disclosure, the paddle method and thedynamic dispensing method are preferred, and the dynamic dispensingmethod is more preferred.

Developing temperature is preferably in the range of 5 to 60° C., morepreferably in the range of 10 to 40° C. The time for developing ispreferably 5 to 300 seconds, more preferably 5 to 90 seconds. For thedynamic dispensing method, the time for developing is preferably 5 to 30seconds. For the paddle method, the time for developing is preferably 20to 60 seconds.

After development, the photoresist pattern formed is preferably washedwith a rinse agent. Such rinse agent is not limited as long as it isincapable of dissolving a photoresist pattern. Examples of the agentinclude solvents which contain organic solvents other than theabove-mentioned developers, such as alcohol agents or ester agents.After washing, the residual rinse agent remained on the substrate orphotoresist film is preferably removed therefrom.

<Application>

The photoresist composition of the present disclosure is useful forexcimer laser lithography such as with ArF, KrF, electron beam (EB)exposure lithography or extreme-ultraviolet (EUV) exposure lithography,and is more useful for electron beam (EB) exposure lithography, ArFexcimer laser exposure lithography and extreme-ultraviolet (EUV)exposure lithography. The photoresist composition of the presentdisclosure can be used in semiconductor microfabrication.

EXAMPLES

All percentages and parts expressing the contents or amounts used in theExamples and Comparative Examples are based on mass, unless otherwisespecified.

The weight average molecular weight is a value determined by gelpermeation chromatography.

Equipment: HLC-8120 GCP type (Tosoh Co. Ltd.)

Column: TSK gel Multipore HXL-M×3+guardcolumn (Tosoh Co. Ltd.)

Eluant: tetrahydrofuran

Flow rate: 1.0 mL/min.

Detecting device: RI detector

Column temperature: 40° C.

Injection amount: 100 μL

Standard material for calculating molecular weight: standard polystyrene(Tosoh Co. ltd.)

Structures of compounds were determined by mass spectrometry (LiquidChromatography: 1100 Type, manufactured by AGILENT TECHNOLOGIES LTD.,Mass Spectrometry: LC/MSD Type, manufactured by AGILENT TECHNOLOGIESLTD.).

Reference Synthesis Example 1

To a reactor, 10 parts of the compound represented by formula (I-1-a),24.01 parts of the compound represented by formula (I-1-b), 32 parts ofmethanol and 1.2 parts of hydrochloric acid were added, and the obtainedmixture was stirred at 23° C. for 8 hours. To the obtained reactionmixture, 390 parts of ethyl acetate and 50 parts of 10% aqueouspotassium carbonate solution and they were stirred it at 23° C. for 30minutes, followed by being left to obtain an organic layer byseparation. To the collected organic layer, 120 parts of ion exchangedwater was added and stirred at 23° C. for 30 minutes, followed by beingleft to obtain an organic layer by separation: The step of washing withwater was conducted three times. Then the collected organic layer wasconcentrated to collect 6.09 parts of the compound represented byformula (I-1-c).

To a reactor, 6.09 parts of the compound represented by formula (I-1-c),72.15 parts of tetrahydrofuran, 2.39 parts of pyridine and 0.15 parts ofdimethylaminopyridine were added, and the obtained mixture was stirredat 23° C. for 30 minutes, followed by being cooled to 5° C. To thecooled mixture, 4.26 parts of the compound represented by formula(I-1-d) was added at 5° C., and the obtained mixture was stirred at 5°C. for 30 minutes and then at 23° C. for 3 hours to conduct thereaction. To the obtained reaction mixture, 400 parts of ethyl acetateand 20 parts of 5% aqueous oxalic acid solution were added and themixture was stirred at 23° C. for 30 minutes, followed by being left tostand to obtain an organic layer by separation. To the collected organiclayer, 60 parts of ion exchanged water was added and the mixture wasstirred at 23° C. for 30 minutes, followed by being left to stand toobtain an organic layer by separation. To the collected organic layer,12 parts of 10% aqueous potassium carbonate solution was added, and thenthe mixture was stirred at 23° C. for 30 minutes: The step of washingwith water was conducted twice. To the collected organic layer, 90 partsof ion exchanged water was added and the mixture was stirred at 23° C.for 30 minutes, followed by being left to stand to obtain an organiclayer by separation: The step of washing with water was conducted fourtimes. Then the collected organic layer was concentrated to collect 6.81parts of the compound represented by formula (I-1).

MASS: 312.2 (Molecular ion peak)

Synthesis Examples of Resins

The monomers used for Synthesis Examples of the resins are shown below.These monomers are referred to as “monomer (X)” where “(X)” is thesymbol of the formula representing the structure of each monomer. Forexample, monomer (a1-0-1) represents the monomer represented by formula(a1-0-1).

The compounds in which an acid has been removed from the monomer (a1)are shown below. The compound represented by formula (xx1) is formed byremoving an acid from Monomer (a1-0-1), Monomer (a1-0-10), Monomer(a1-1-2), Monomer (a1-1-3), Monomer (a1-2-9) or Monomer (a1-2-11). Thecompound represented by formula (xx2) is formed by removing an acid fromMonomer (I-1). The compound represented by formula (xx3) is formed byremoving an acid from Monomer (X-1). The compound represented by formula(xx4) is formed by removing an acid from Monomer (X-2).

Each of these monomers and the above-mentioned compounds shows Hansensolubility parameters as listed in Table 1. The parameters listedtherein were determined using HSPiP version 4.1.

TABLE 1 The difference formula δd δp δh R of R (a1-0-1) 15.2 3.0 3.92.77 5.00 (a1-0-10) 16.5 2.1 1.7 5.07 2.70 (a1-1-2) 16.8 3.0 2.5 4.353.42 (a1-1-3) 16.7 2.6 1.9 4.88 2.89 (a1-2-9) 16.6 2.9 3.6 3.24 4.53(a1-2-11) 16.4 2.4 2.9 3.83 3.94 (a2-1-1) 17.5 5.9 7.4 4.20 — (a2-1-3)18.1 8.0 10.9 7.80 — (a3-1-1) 17.1 11.1 7.3 7.91 — (a3-2-1) 17.3 9.1 5.06.31 — (a3-2-3) 17.3 9.8 6.3 6.80 — (a3-4-2) 17.1 9.6 5.9 6.46 — (x-1)17.3 5.2 5.2 3.53 8.23 (x-2) 16.7 5.5 3.9 3.50 2.20 (I-1) 17.0 6.2 5.13.67 5.16 (xx1) 16.1 6.8 13.4 7.77 — (xx2) 16.8 8.7 13.3 8.83 — (xx3)17.0 8.2 16.9 11.76 — (xx4) 17.0 7.1 10.2 5.70 —

Synthesis Example 1

Monomer (a1-1-2), monomer (a1-2-9), monomer (I-1), monomer (a2-1-1) andmonomer (a3-4-2) were mixed together with the mole ratio of the monomersbeing 15:25:10:2.5:47.5 [monomer (a1-1-2):monomer (a1-2-9): monomer(I-1):monomer (a2-1-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated at 75° C. for about 5hours. Then, the obtained reaction mixture was poured into a largeamount of a mixture of methanol and ion exchanged water to precipitate aresin. The obtained resin was filtrated. The obtained resin wasdissolved in propyleneglycolmonomethylether acetate to obtain asolution, and the solution was poured into a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. These operations were conducted twice to provide the resinhaving a weight average molecular weight of about 7900 in 86% yield.This resin, which had the structural units of the following formulae,was referred to Resin A1.

Synthesis Example 2

Monomer (a1-1-2), monomer (a1-2-9), monomer (I-1), monomer (a2-1-1) andmonomer (a3-4-2) were mixed together with the mole ratio of the monomersbeing 20:25:5:2.5:47.5 [monomer (a1-1-2):monomer (a1-2-9):monomer(I-1):monomer (a2-1-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 7700 in 82% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A2.

Synthesis Example 3

Monomer (a1-1-2), monomer (a1-2-9), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-2-9):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8200 in 86% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A3.

Synthesis Example 4

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8500 in 80% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A4.

Synthesis Example 5

Monomer (a1-1-3), monomer (a1-2-9), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-3):monomer (a1-2-9):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 7900 in 70% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A5.

Synthesis Example 6

Monomer (a1-1-3), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-3):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8200 in 68% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A6.

Synthesis Example 7

Monomer (a1-1-2), monomer (a1-2-9), monomer (I-1) and monomer (a3-2-1)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-2-9):monomer (I-1):monomer (a3-2-1)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8400 in 86% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A7.

Synthesis Example 8

Monomer (a1-1-2), monomer (a1-2-9), monomer (X-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-2-9):monomer (X-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8400 in 86% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A8.

Synthesis Example 9

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 5:40:5:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8700 in 88% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A9.

Synthesis Example 10

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 10:35:5:50[monomer (a1-1-2):monomer (a1-2-11): monomer (I-1):monomer (a3-4-2)],and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Using the mixture, a resin was produced in the samemanner as Synthesis Example 1. The obtained resin had a weight averagemolecular weight of about 8500 in 86% yield. This resin, which had thestructural units of the following formulae, was referred to Resin A10.

Synthesis Example 11

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 15:30:5:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8400 in 84% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A11.

Synthesis Example 12

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being25:20:5:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer(a3-4-2)], and propyleneglycolmonomethylether acetate was added theretoin the amount equal to 1.5 times by mass of the total amount of monomersto obtain a solution. Using the mixture, a resin was produced in thesame manner as Synthesis Example 1. The obtained resin had a weightaverage molecular weight of about 8000 in 80% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A12.

Synthesis Example 13

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:27:3:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8200 in 82% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A13.

Synthesis Example 14

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:23:7:50[monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8600 in 78% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin A14.

Synthesis Example 15

Monomer (a1-1-2), monomer (a1-2-11), monomer (I-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being20:20:10:50 [monomer (a1-1-2):monomer (a1-2-11):monomer (I-1):monamer(a3-4-2)], and propyleneglycolmonomethylether acetate was added theretoin the amount equal to 1.5 times by mass of the total amount of monomersto obtain a solution. Using the mixture, a resin was produced in thesame manner as Synthesis Example 1. The obtained resin had a weightaverage molecular weight of about 8400 in 75% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A15.

Synthesis Example 16

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-3) and monomer(a3-4-2) were mixed together with the mole ratio of the monomers being45:14:2.5:38.5 [monomer (a1-1-3):monomer (a1-2-9):monomer(a2-1-3):monomer (a3-4-2)], and propyleneglycolmonomethylether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Using the mixture, a resin wasproduced in the same manner as Synthesis Example 1. The obtained resinhad a weight average molecular weight of about 7600 in 68% yield. Thisresin, which had the structural units of the following formulae, wasreferred to Resin AX1.

Synthesis Example 17

Monomer (a1-1-2), monomer (a1-2-9), monomer (X-2) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-2-9):monomer (X-2):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8300 in 86% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin AX2.

Synthesis Example 18

Monomer (a1-1-2), monomer (a1-0-1), monomer (X-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2):monomer (a1-0-1):monomer (X-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8900 in 78% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin AX3.

Synthesis Example 19

Monomer (a1-0-10), monomer (a1-2-9), monomer (X-1) and monomer (a3-4-2)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-0-10):monomer (a1-2-9):monomer (X-1):monomer (a3-4-2)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8700 in 75% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin AX4.

Synthesis Example 20

Monomer (a1-1-2), monomer (a1-2-9), monomer (X-1) and monomer (a3-1-1)were mixed together with the mole ratio of the monomers being 20:25:5:50[monomer (a1-1-2): monomer (a1-2-9):monomer (X-1):monomer (a3-1-1)], andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Using the mixture, a resin was produced in the same manner asSynthesis Example 1. The obtained resin had a weight average molecularweight of about 8100 in 85% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin AX5.

Synthesis Example 21

To a mixture of Monomer (a5-1-1) and monomer (a4-0-12) the molar ratioof which was 50:50, methylisobutylketone was added in the amount equalto 1.2 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile was added as initiators to the solutionin the amounts of 3% by mole respectively with respect to the totalamount of monomers, and the resultant mixture was heated at 70° C. forabout 5 hours. The obtained reaction mixture was poured into a largeamount of a mixture of methanol and ion exchanged water to precipitate aresin. The obtained resin was filtrated to provide the copolymer havinga weight average molecular weight of about 10000 in 91% yield. Thisresin, which had the structural units of the following formulae, wasreferred to Resin X1.

(Preparing Photoresist Compositions)

Photoresist compositions were prepared by mixing and dissolving each ofthe components shown in Table 2, and then filtrating through afluororesin filter having 0.2 μm pore diameter.

TABLE 2 Acid Quencher Resin Generator (D) Photoresist (Kind/ (B) ((Kind/Comp. parts) (Kind/parts) parts) PB/PEB Composition 1 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A1/10 B1-22/0.45 Composition 2 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A2/10 B1-22/0.45 Composition 3 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A3/10 B1-22/0.45 Composition 4 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A4/10 B1-22/0.45 Composition 5 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A5/10 B1-22/0.45 Composition 6 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A6/10 B1-22/0.45 Composition 7 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A7/10 B1-22/0.45 Composition 8 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A8/10 B1-22/0.45 Composition 9 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A9/10 B1-22/0.45 Composition 10 X1/0.2 B1-21/0.90D1/0.28 100° C./95° C. A10/10 B1-22/0.45 Composition 11 X1/0.2B1-21/0.90 D1/0.28 100° C./95° C. A11/10 B1-22/0.45 Composition 12X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C. A12/10 B1-22/0.45 Composition13 X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C. A13/10 B1-22/0.45Composition 14 X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C. A14/10B1-22/0.45 Composition 15 X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C.A15/10 B1-22/0.45 Comparative X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C.Composition 1 AX-1/10 B1-22/0.45 Comparative X1/0.2 B1-21/0.90 D1/0.28100° C./95° C. Composition 2 AX-2/10 B1-22/0.45 Comparative X1/0.2B1-21/0.90 D1/0.28 100° C./95° C. Composition 3 AX-3/10 B1-22/0.45Comparative X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C. Composition 4AX-4/10 B1-22/0.45 Comparative X1/0.2 B1-21/0.90 D1/0.28 100° C./95° C.Composition 5 AX-5/10 B1-22/0.45

The symbols listed in Table 2 represent the following ones.

<Resin>

A1 to A15, AX-1 to AX-5: Resins A1 to A15, Resins AX-1 to AX-5, eachprepared by the methods as described above.

<Acid Generator (B)>

B1-21: The salt represented by the formula (B1-21), prepared accordingto JP2012-224611A1

B1-22: The salt represented by the formula (B1-22), prepared accordingto JP2012-224611A1

<Quencher (D)>

D1: The compound as follow, a product of Tokyo Chemical Industry Co.,LTD

<Solvent for Photoresist Compositions>

Propyleneglycolmonomethyl ether acetate 265 parts Propyleneglycolmonomethyl ether 20 parts 2-Heptanone 20 partsγ-butyrolactone 3.5 parts 

<Producing Photoresist Patterns>

A composition for an organic antireflective film (“ARC-29”, by NissanChemical Co. Ltd.) was applied onto 12-inch silicon wafer and baked for60 seconds at 205° C. to form a 78 nm thick organic antireflective film.

One of the photoresist compositions was then applied thereon by spincoating in such a manner that the thickness of the film after drying(pre-baking) became 85 nm.

The obtained wafer was then pre-baked for 60 seconds on a direct hotplate at the temperature given in the “PB” column in Table 2.

On the wafers on which the photoresist film had thus formed, the filmwas then exposed through a mask for forming contact hole patterns (holepitch 90 nm/hole diameter 55 nm) while changing exposure quantitystepwise, with an ArF excimer laser stepper for liquid-inmersionlithography (“XT:1900Gi” by ASML Ltd.: NA=1.35, ¾ Annular X-Y-pol.lighting). Ultrapure water was used as medium for liquid-immersion.

After the exposure, post-exposure baking was carried out for 60 secondsat the temperature given in the “PEB” column in Table 2.

Then, development was carried out with butyl acetate (a product of TokyoChemical Industry Co., LTD) at 23° C. for 20 seconds in the manner ofdynamic dispensing method to obtain negative photoresist patterns.

<Evaluation of Mask Error Factor [MEF]>

Negative photoresist patterns were produced in the same manner asrecited in “Producing photoresist patterns”, conducting exposure with aneffective sensitivity and using a mask the hole diameter of which was 57nm, 56 nm, 55 nm, 54 nm or 53 nm and the hole pitches of which was 90nm. In this evaluation, the effective sensitivity was determined as theexposure quantity at which the photoresist pattern having 45 nm holediameter was obtained by the exposure using the above-mentioned mask.The results were plotted along the abscissa axis representing diametersof mask holes and along the ordinate axis representing diameters of theholes of the photoresist patterns formed (transferred) on the substrateby exposure.

The slope of a plotted regression line, i.e., the increment of theordinate per the increment by 1 of the abscissa, was determined as theMEF value.

When the MEF value was 4.6 or less, MEF was evaluated as being good andexpressed by ∘∘;

when the MEF value was greater than 4.6 to not greater than 4.8, MEF wasevaluated as being good and expressed by ∘; and when the MEF value wasgreater than 4.8, MEF was evaluated as being not good and expressed byx.

The results are shown in Table 3. The numerical values in parenthesesrepresent MEF values.

<Evaluation as to Critical Dimension Uniformity (CDU)>

In this evaluation, effective sensitivity was determined as the exposurequantity at which the photoresist pattern having 50 nm of hole diameterwas obtained by the exposure using the above-mentioned mask.

The photoresist patterns having 55 nm of hole diameter were formed bythe same method as described above in which exposure was conducted atthe effective sensitivity.

The hole diameter was measured at 24 points per one hole of the pattern.

The average of the values determined as the hole diameter was defined asthe average hole diameter of the hole.

As to the average hole diameter, the standard deviation was obtainedbased on the population which consisted of 400 holes within the samewafer.

When the standard deviation was not more than 1.8 nm, it was evaluatedas “∘∘” (very good). When the standard deviation was from more than 1.8nm to 2 nm, it was evaluated as “∘” (bad).

When the standard deviation was more than 2 nm, it was evaluated as “X”(bad). Table 3 illustrates the results thereof. The parenthetical numberin each column of “CDU” represents the standard deviation (nm).

TABLE 3 Photoresist Composition MFR CDU Ex. 1 Composition 1 ∘∘ (4.58) ∘∘(1.73) Ex. 2 Composition 2 ∘∘ (4.57) ∘∘ (1.71) Ex. 3 Composition 3 ∘∘(4.55) ∘∘ (1.68) Ex. 4 Composition 4 ∘∘ (4.56) ∘∘ (1.65) Ex. 5Composition 5 ∘∘ (4.59) ∘∘ (1.66) Ex. 6 Composition 6 ∘∘ (4.60) ∘∘(1.65) Ex. 7 Composition 7 ∘∘ (4.52) ∘∘ (1.76) Ex. 8 Composition 8 ∘∘(4.55) ∘∘ (1.71) Ex. 9 Composition 9 ∘∘ (4.58) ∘∘ (1.71) Ex. 10Composition 10 ∘∘ (4.54) ∘∘ (1.68) Ex. 11 Composition 11 ∘∘ (4.55) ∘∘(1.66) Ex. 12 Composition 12 ∘∘ (4.59) ∘∘ (1.70) Ex. 13 Composition 13∘∘ (4.60) ∘∘ (1.71) Ex. 14 Composition 14 ∘∘ (4.58) ∘∘ (1.65) Ex. 15Composition 15 ∘∘ (4.60) ∘∘ (1.67) Comparative Comparative ∘ (4.75) ∘∘(1.74) Ex. 1 Composition 1 Comparative Comparative x (4.84) ∘ (1.88) Ex.2 Composition 2 Comparative Comparative x (4.89) ∘ (1.83) Ex. 3Composition 3 Comparative Comparative x (5.06) x (2.17) Ex. 4Composition 4 Comparative Comparative x (5.12) x (2.22) Ex. 5Composition 5

The photoresist composition of the disclosure can provide a photoresistpattern with excellent CDU or MFR. Therefore, the photoresistcomposition can be used for semiconductor microfabrication.

What is claimed is:
 1. A photoresist composition comprising an acidgenerator and a resin which comprises one or more structural units (a1)derived from a monomer (a1) having an acid-liable group, the monomer(a1) each showing a distance of Hansen solubility parameters between themonomer (a1) and butyl acetate in the range of 3 to 5, the distancebeing calculated from formula (1):R=(4×(δd _(m)−15.8)²+(δp _(m)−3.7)²+(δh _(m)−6.3)²)^(1/2)  (1) in whichδd_(m) represents a dispersion parameter of a monomer, δp_(m) representsa polarity parameter of a monomer, δh_(m) represents a hydrogen bondingparameter of a monomer, and R represents a distance of Hansen solubilityparameters, and at least one of monomers (a1) showing a difference of Rbetween the monomer (a1) and a compound in which an acid is removed fromthe monomer (a1) in the range of not less than 5, wherein the monomershowing a difference of R between the monomer (a1) and a compound inwhich an acid is removed from the monomer (a1) in the range of not lessthan 5 is the monomer represented by formula (I):

in the formula, X^(a) and X^(b) represent an oxygen atom or a sulfuratom, W² represents a C3 to C36 alicyclic hydrocarbon group which canhave a substituent and a methylene group of which can be replaced by anoxygen atom, a sulfur atom, a carboxy group or a sulfonyl group, R¹represents a C1 to C8 alkyl group in which a methylene group can bereplaced by an oxygen atom or a carboxy group, R² represents a hydrogenatom or a methyl group, A¹ represents a single bond or a C1 to C24divalent saturated hydrocarbon group where a methylene group can bereplaced by an oxygen atom or a carbonyl group, and X¹ represents agroup represented by formulae (X¹-1) to (X¹-4):

where * and ** represent a binding position respectively, and **represents a binding position to A¹.
 2. The photoresist compositionaccording to claim 1 wherein the resin further comprises a structuralunit derived from a monomer (s) having no acid-liable group, and R ofthe monomer (s) is not more than 6.7.
 3. The photoresist compositionaccording to claim 2 wherein each of the monomers (a1) shows thedifference in the range of not less than 2.8.
 4. The photoresistcomposition according to claim 1 wherein the ratio of a structural unitderived from the monomer (a1) showing the difference in the range of notless than 4.5 is not less than 30% by mole with respect to all thestructural units of the resin.
 5. The photoresist composition accordingto claim 1 wherein the resin further comprises a structural unit havinga lactone ring and no acid-labile group.
 6. The photoresist compositionaccording to claim 5 wherein the structural unit having a lactone ringand no acid-labile group is a structural unit represented by formula(a3-4):

wherein R^(a24) represents a hydrogen atom, a halogen atom or a C1 to C6alkyl group which can have a halogen atom, L^(a7) represents —O—,*—O-L^(a8)-O—, *—O-L^(a8)-CO—O—, *—O-L^(a8)-CO—O-L^(a9)-CO—O— or*—O—R^(a8)—O—CO-L^(a9)-O— where * represents a binding position to acarbonyl group, L^(a8) and L^(a9) independently represents a C1 to C6alkanediyl group, and R^(a25) in each occurrence represents a carboxygroup, a cyano group or a C1 to C4 aliphatic hydrocarbon group, and w1represents an integer of 0 to
 8. 7. The photoresist compositionaccording to claim 1 wherein the resin further comprises a structuralunit having a hydroxyl group and no acid-labile group.
 8. Thephotoresist composition according to claim 1 wherein the acid generatoris represented by formula (B1):

wherein Q¹ and Q² each respectively represent a fluorine atom or a C1 toC6 perfluoroalkyl group, L^(b1) represents a C1 to C24 divalentsaturated hydrocarbon group where a methylene group can be replaced byan oxygen atom or a carbonyl group and a hydrogen atom can be replacedby a hydroxyl group or fluorine atom, and Y represents an optionallysubstituted methyl group or an optionally substituted C3 to C18alicyclic hydrocarbon group where a methylene group can be replaced byan oxygen atom, a carbonyl group or a sulfonyl group, and Z⁺ representsan organic cation.
 9. The photoresist composition according to claim 1further comprising a resin which comprises a structural unit having afluorine atom and no acid-labile group.
 10. The photoresist compositionaccording to claim 1 further comprising a salt which generates an acidhaving an acidity weaker than an acid generated from the acid generator.11. A method for producing a photoresist pattern comprising steps (1) to(5); (1) applying the photoresist composition according to claim 1 ontoa substrate; (2) drying the applied composition to form a compositionlayer; (3) exposing the composition layer; (4) heating the exposedcomposition layer; and (5) developing the heated composition layer. 12.A photoresist composition comprising an acid generator and a resin whichcomprises one or more structural units (a1) derived from a monomer (a1)having an acid-liable group, the monomer (a1) each showing a distance ofHansen solubility parameters between the monomer (a1) and butyl acetatein the range of 3 to 5, the distance being calculated from formula (1):R=(4×(δd _(m)−15.8)²+(δp _(m)−3.7)²+(δh _(m)−6.3)²)^(1/2)  (1) in whichδd_(m) represents a dispersion parameter of a monomer, δp_(m) representsa polarity parameter of a monomer, δh_(m) represents a hydrogen bondingparameter of a monomer, and R represents a distance of Hansen solubilityparameters, and at least one of monomers (a1) showing a difference of Rbetween the monomer (a1) and a compound in which an acid is removed fromthe monomer (a1) in the range of not less than 5, wherein the resinfurther comprises a structural unit represented by formula (a3-4):

wherein R^(a24) represents a hydrogen atom, a halogen atom or a C1 to C6alkyl group which can have a halogen atom, L^(a7) represents —O—,*—O-L^(a8)-O—, *—O-L^(a8)-CO—O—, *—O-L^(a8)-CO—O-L^(a9)-CO—O— or*—O-L^(a8)-O—CO-L^(a9)-O— where * represents a binding position to acarbonyl group, L^(a8) and L^(a9) independently represents a C1 to C6alkanediyl group, and R^(a25) in each occurrence represents a carboxygroup, a cyano group or a C1 to C4 aliphatic hydrocarbon group, w1represents an integer of 0 to 8, and the structural unit represented byformula (a3-4) has no acid labile group.
 13. The photoresist compositionaccording to claim 12 wherein the resin further comprises a structuralunit derived from a monomer (s) having no acid-liable group, and R ofthe monomer (s) is not more than 6.7.
 14. The photoresist compositionaccording to claim 13 wherein each of the monomers (a1) shows thedifference in the range of not less than 2.8.
 15. The photoresistcomposition according to claim 12 wherein the ratio of a structural unitderived from the monomer (a1) showing the difference in the range of notless than 4.5 is not less than 30% by mole with respect to all thestructural units of the resin.
 16. The photoresist composition accordingto claim 12 wherein the resin further comprises a structural unit havinga hydroxyl group and no acid-labile group.
 17. The photoresistcomposition according to claim 12 wherein the acid generator isrepresented by formula (B1):

wherein Q¹ and Q² each respectively represent a fluorine atom or a C1 toC6 perfluoroalkyl group, L^(b1) represents a C1 to C24 divalentsaturated hydrocarbon group where a methylene group can be replaced byan oxygen atom or a carbonyl group and a hydrogen atom can be replacedby a hydroxyl group or fluorine atom, and Y represents an optionallysubstituted methyl group or an optionally substituted C3 to C18alicyclic hydrocarbon group where a methylene group can be replaced byan oxygen atom, a carbonyl group or a sulfonyl group, and Z⁺ representsan organic cation.
 18. The photoresist composition according to claim 12further comprising a resin which comprises a structural unit having afluorine atom and no acid-labile group.
 19. The photoresist compositionaccording to claim 12 further comprising a salt which generates an acidhaving an acidity weaker than an acid generated from the acid generator.20. A method for producing a photoresist pattern comprising steps (1) to(5); (1) applying the photoresist composition according to claim 12 ontoa substrate; (2) drying the applied composition to form a compositionlayer; (3) exposing the composition layer; (4) heating the exposedcomposition layer; and (5) developing the heated composition layer.